A new study suggests that the conversational pace of everyday life may be so brisk it hampers the ability of some children for distinguishing discrete sounds and words and, the result is, to make sense of speech.

A. it hampers the ability of some children for distinguishing discrete sounds and words and, the result is, to make
B. that it hampers the ability of some children to distinguish discrete sounds and words and, as a result, to make
C. that it hampers the ability of some children to distinguish discrete sounds and words and, the result of this, they are unable to make
D. that it hampers the ability of some children to distinguish discrete sounds and words, and results in not making
E. as to hamper the ability of some children for distinguishing discrete sounds and words, resulting in being unable to make

OA is B
What is the best modifier to use for this question? Is OA truly correct, I need the explanation of an Expert.