请教蓝皮书的2个问题,谢谢NN们

1, the record of the past is always incomplete, and the historian who writes about it inevitably reflects the preoccupations of their own time.

A: ...

B:the historian writing about it will inevitably reflect

C:historians in writing about it inevitale reflect

the answer is C. however, I don't find enough reasons to support it

2, several studies have found that the coronary patients who exercise most actively have half or less than half the chance of dying of a heart attack as those who are sedentary.

A:...

B:are at least fifty percent less likely than those who are sedentary to die of a heart attack.

the answer given by the BLUEBOOK is B, however, on Page 297 of the Vocabulary Red Book written by Yn Minhong, the full sample sentence is like A. NNs, who can help me?

THx THX THX

1中D,E是什么?单从ABC看，因为后面的of their own time, 只有C的historians对

2答案是B