问一道Prep上的数学题

tomomi

请教以下prep的题：

37.5000-!-item-!-187;#058&004365

For every integer k from 1 to 10, inclusive, the kth term of a certain sequence is given by (-1)^k+1(1/2^k) （负1的k加1次方，乘以2的k次方分之一） If T is the sum of the first 10 terms in the sequence, then T is

(A) greater than 2

(B) between 1 and 2

(C) between 1/2 and 1

(D) between 1/4 and 1/2

(E) between 1/4

请教，答案为什么是D呢？怎样的思路？
谢谢！