The United States: Fliers may want to have their tickets in hand before catching their planes, but the airline companies are doing everything they can to bring forward cost-saving ticketless flight--no paper needed, just a ticket number and a photo ID. Anyone who buys a Northwest E-ticket through the airline's computer service by June 16 will get an award. Next time you fly, you can buy another ticket for a friend for $99, good anywhere in the US or Canada, along with the lowest ticket prices. Some airlines offer extra frequent-flier miles for the ticketless crowd. And there are rising punishments for paper lovers. American, Northwest, United, and US Airways have raised the cost for lost-ticket replacement to $70 from either $60 or $50. The airlines insist that the increase in price is not meant to push travelers toward E-tickets but only covers the increasing cost of replacing and tracking a missing ticket. To encourage people to take ticketless flights, the airlines   _  .
sell their tickets for $99 from June to the following year let travelers go to both the US and Canada with the same tickets allow each traveler to have an extra $99 ticket for a friend of theirs offer ticketless travelers free miles to fly in the US
Question: The United States: Fliers may want to have their tickets in hand before catching their planes, but the airline companies are doing everything they can to bring forward cost-saving ticketless flight--no paper needed, just a ticket number and a photo ID. Anyone who buys a Northwest E-ticket through the airline's computer service by June 16 will get an award. Next time you fly, you can buy another ticket for a friend for $99, good anywhere in the US or Canada, along with the lowest ticket prices. Some airlines offer extra frequent-flier miles for the ticketless crowd. And there are rising punishments for paper lovers. American, Northwest, United, and US Airways have raised the cost for lost-ticket replacement to $70 from either $60 or $50. The airlines insist that the increase in price is not meant to push travelers toward E-tickets but only covers the increasing cost of replacing and tracking a missing ticket. To encourage people to take ticketless flights, the airlines   _  .
A. sell their tickets for $99 from June to the following year
B. let travelers go to both the US and Canada with the same tickets
C. allow each traveler to have an extra $99 ticket for a friend of theirs
D. offer ticketless travelers free miles to fly in the US
Answer: