A new study suggests that the conversational

[patanjali.purpose]

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-B

Key doubt: why is THE RESULT IS in A and THE RESULT OF THIS in C are incorrect? When such short phrases(even clauses) could be OK especially when they are non-essential (separated by 2 commas)

[srcc25anu]

Hampers the ABILITY TO DO SOMETHING
Hence eliminate A and E
Now checkfor //ism: hampers the ability to DISTINGUISH DISCRETE SOUND and to MAKE sense of speech
Hence B

[ceilidh.erickson]

The issue is not that THE RESULT IS and THE RESULT OF THIS are wrong in the abstract; they're just wrong/unnecessary in the context of this sentence.

Here, we want parallelism between HAMPERS THE ABILITY... TO DISTINGUISH... AND TO MAKE. If we say instead "the result is to make," we destroy the intended parallelism. Not only that, but the meaning would be lost. "The result is to make sense of speech" implies that children can make sense of speech. Clearly, the intended meaning is that the ability to make sense of speech is hampered.

Furthermore, C is missing a verb. It would need to say "the result of this is something."

[Crystal W]

Can someone introduce so as to? I do not understand it meaning and I do not know if it is correct to use? In OG 2016, SC 34 said this phrase is incorrect.
Thanks in advance !