Last summer, after finishing our work in China, I took a trip of a lifetime on the Trans-Siberian Railway. Leaving Beijing early on a Wednesday morning in July, my wife and I traveled through some gorgeous countryside before we arrived in Moscow the following Monday evening. The first part of the journey took us past the Great Wall and through the grasslands of Inner Mongolia. At the Mongolian Republic border, we had a delay  while the wheels were changed because the railway is different. On our way to the capital, Ulan Bator, we saw herdsmen  on horseback looking after their cattle. There was a terrible thunderstorm as we crossed a vast open plain. Later we had a quick tour of Ulan Bator. Next, the train took us into Siberia. After a stop at Irkutsk, a popular holiday resort  , where a tour group left the train, we passed the great Lake Baikal. Later, we saw some lovely wooden houses in pretty, sunny countryside. This surprised us, as we had imagined Siberia as being covered in thick snow. Over the next few days, we passed through Novosibirsk, Omsk and other cities in the heartlands of the Russian Federation. By now, our body clocks were losing their sense of time. We wanted to sleep and eat at the wrong time! At last we reached Moscow. We were too tired and slept for 16 hours that night. The next day we went sightseeing. We saw the Kremlin and some other great buildings in the Russian capital. Then, all too soon, it was time for us to return to our home in London. The author was surprised by what he saw in Siberia because   _  .
it was covered with thick snow though it was sunny. the houses there were so pretty. there were a large number of tourists there. It was not covered in snow but it was sunny.
Question: Last summer, after finishing our work in China, I took a trip of a lifetime on the Trans-Siberian Railway. Leaving Beijing early on a Wednesday morning in July, my wife and I traveled through some gorgeous countryside before we arrived in Moscow the following Monday evening. The first part of the journey took us past the Great Wall and through the grasslands of Inner Mongolia. At the Mongolian Republic border, we had a delay  while the wheels were changed because the railway is different. On our way to the capital, Ulan Bator, we saw herdsmen  on horseback looking after their cattle. There was a terrible thunderstorm as we crossed a vast open plain. Later we had a quick tour of Ulan Bator. Next, the train took us into Siberia. After a stop at Irkutsk, a popular holiday resort  , where a tour group left the train, we passed the great Lake Baikal. Later, we saw some lovely wooden houses in pretty, sunny countryside. This surprised us, as we had imagined Siberia as being covered in thick snow. Over the next few days, we passed through Novosibirsk, Omsk and other cities in the heartlands of the Russian Federation. By now, our body clocks were losing their sense of time. We wanted to sleep and eat at the wrong time! At last we reached Moscow. We were too tired and slept for 16 hours that night. The next day we went sightseeing. We saw the Kremlin and some other great buildings in the Russian capital. Then, all too soon, it was time for us to return to our home in London. The author was surprised by what he saw in Siberia because   _  .
A. it was covered with thick snow though it was sunny.
B. the houses there were so pretty.
C. there were a large number of tourists there.
D. It was not covered in snow but it was sunny.
Answer: