(单选题)

According to Para.2, the atmosphere on Mars would ______.

A.sustain life more easily than Moon

B.give human colonists a safety shield against dangerous cosmic effects

C.protect humans completely from harmful cosmic radiation coming from space

D.change the genetic makeup of humans and cause their DNA to change and mutate

参考答案：B

参考解析：

细节理解题。该题可定位到第二段第二句“The atmosphere is important because it protects humans and all other life from a continuous attack of radiation caused by sources such as the sun.”及最后一句话“Although Mars’ atmosphere is significantly thinner than Earths’, at least it has one and would create some sort of protective barrier for humans.”，由此可知，尽管火星的大气层比地球的要稀薄地多，但至少火星有大气，这会给人类创造某种保护屏障。所以根据第二段，火星的大气保护使人们免受辐射对人们造成的危害。故选B。

知识点：