Barack Obama makes his first trip to Asia as president this week, leaving behind a host of domestic   problems with the visit that recognizes the region's economic and diplomatic importance. "Obama"s trip includes stops in Japan, Singapore, China and South Korea, and his message will be simple, says Nicolas Lardy at the Peterson Institute for International Economics. "Well, I think his broadest aim is to convince Asians that the United States is fully committed to the region that we have an agenda that's much broader than they saw over the past eight years of the very heavy focus on anti-terrorism." Obama's first stop is Japan, where he meets with the new Prime Minister Yukio Hatoyama who has promised to steer a diplomatic course more independent of Washington. While Japan is seen as a getting-to-know-you stop, when Obama heads to the Singapore for the APEC meeting, he will likely face pressure on trade. "Many Asians are concerned about what US trade policy will be, and they've been somewhat alarmed by the fact that the president really hasn't set out very much revision for what US trade policy is in his administration." But the critical _ of the trip will come in China, his third stop where Obama will have to navigate the complex relationship with the country that is the largest holder of US debt. "As you say, you know, if you owe the bank one dollar, it's your problem, if you owe the bank, you know, 3 million dollars, it's the bank's problem, so it's similar with China. I mean they have no interest in trying to use the influence with us, because eventually, they're the one that they own all those dollars." Also on the table will be North Korea and Iran's nuclear ambitions as well as cooperation on Afghanistan. With Obama enjoying sky high popularity level in the countries he is visiting, detailed results may be beside the point, given that Obama is still in his first year in office, analysts say this trip is mostly about laying the ground work for the future. The author develops the passage mainly  _  .
by examples by cause and effect by comparison by order in time
Question: Barack Obama makes his first trip to Asia as president this week, leaving behind a host of domestic   problems with the visit that recognizes the region's economic and diplomatic importance. "Obama"s trip includes stops in Japan, Singapore, China and South Korea, and his message will be simple, says Nicolas Lardy at the Peterson Institute for International Economics. "Well, I think his broadest aim is to convince Asians that the United States is fully committed to the region that we have an agenda that's much broader than they saw over the past eight years of the very heavy focus on anti-terrorism." Obama's first stop is Japan, where he meets with the new Prime Minister Yukio Hatoyama who has promised to steer a diplomatic course more independent of Washington. While Japan is seen as a getting-to-know-you stop, when Obama heads to the Singapore for the APEC meeting, he will likely face pressure on trade. "Many Asians are concerned about what US trade policy will be, and they've been somewhat alarmed by the fact that the president really hasn't set out very much revision for what US trade policy is in his administration." But the critical _ of the trip will come in China, his third stop where Obama will have to navigate the complex relationship with the country that is the largest holder of US debt. "As you say, you know, if you owe the bank one dollar, it's your problem, if you owe the bank, you know, 3 million dollars, it's the bank's problem, so it's similar with China. I mean they have no interest in trying to use the influence with us, because eventually, they're the one that they own all those dollars." Also on the table will be North Korea and Iran's nuclear ambitions as well as cooperation on Afghanistan. With Obama enjoying sky high popularity level in the countries he is visiting, detailed results may be beside the point, given that Obama is still in his first year in office, analysts say this trip is mostly about laying the ground work for the future. The author develops the passage mainly  _  .
A. by examples
B. by cause and effect
C. by comparison
D. by order in time
Answer: