TTGWD25-36我怎么觉得都不对啊,为什么是B?

初夏的味道

过来看看解释

skigorush

路吉儿

qqiaoer

The chemical adenosine is released by brain cells when those cells are active.
Adenosine then binds to more and more sites on cells in certain areas of thebrain, as the total amount released gradually increases during wakefulness.  随着化学物质Adenosine被脑细胞释放出来的数量在清醒时的逐步增加，A物质越来越多地绑定到大脑的某一区域

During sleep, the number of sites to which adenosine is bound decreases. 睡眠时，A物质被绑定的区域减少（我的理解是和前面那句话说的是一回事，A绑定的越来越多，所以可以给更多的A用来绑定的区域当然就少了）

Some  researchers have hypothesized that it is the cumulative binding of adenosine to a
large number of sites that causes the onset of sleep.
结论：累计的A绑定到大脑某个区域的数量达到一个大的量，这个累积的绑定就引发了睡眠。
注意：THAT从句 that causes the onset of sleep修饰限定的是binding

所以这个题目B的含义和结论要论证的方向完全一致。

其实还是阅读理解的问题，我一开始也晕。