The particular design of muscles and bones in the neck and limbs of the turtle allow that it can draw in its exposed parts such that an attacker can find nothing but hard shell to bite.
allow that it can draw in its exposed parts such that
allow it to draw in its exposed parts, and so
allows for it to draw in its exposed parts and that
allows that it can draw in its exposed parts, and so
allows it to draw in its exposed parts, so that
Allow to do, allow..to do, allow that(不加虚拟)
AD语义不对,allow that表示 同意,承认,不表示允许
B and so没有平行对象
C 允许某人做某事,直接用allow ...to do而不用allow for...to do
E 正确,而且so that 表示结果
参见这道题 http://gmat.kmf.com/question/959j7h.html
so作副词表示如此、那么,如so beautiful,也有这样、如此(指代前面提过的事情)的意思,如:
‘Is he coming?’ ‘ I hope so .’
‘Did they mind?’ ‘I don't think so .’