Please answer the following question: I'm taking a test and have to guess the right answer to the question after the article. Article: Chinese space trainer Wang Yuan has been chosen as one of the volunteers for the Mars-500 test project. He was very happy to be chosen and will accept the meaningful challenge Another five volunteers are all space lovers., including three Russians, an Italy-Colombian and a Frenchman. They are about to feel what it's like to travel to Mars, only without leaving the earth. They are locked up together for a year and a half under a similar condition to the red planet during the whole process. So the experiment is called Mars-500. When reporters asked what they would miss most during the 520-day special life, French trainer Charles said:"For me, it will be mainly my family, the sun and fresh air." The Mars-500 test will be in a special building in Moscow, Russia. Although the people won't leave the building, they will fell as if they are on a real trip to the Mars. The most difficult thing will be to be separated from the people that they used to live with. The trainer won't see sunsets, sunrises, won't feel rain for 18 months. That will be hard. The main task is to study the "Man and environment". It'll care about the astronauts' getting experience and physical effects. The 520-day-test is divided into three parts,the first 250days to Mars, the middle 30days of landing on Mars, the last 240 days to return to the earth. Everyone will stay there alone for a long time and will work lonely. They will have to make decisions themselves and only then report to the earth, and the earth will tell them whether they do the right thing or not. Each astronaut is preparing for the great challenge. It is learned that they will be launched early in June. And the experiment will end in November 2011. Question: The most difficult thing for the trainers is _ . Options: A: no vegetables to eat B: they can't watch TV C: they can't see many people D: they must lie all day
Answer:
C