Insomnia does not usually begin as a physical problem. It can affect one's physical health.
The conjunction yet lets the reader know that a contrast is coming: is not usually . . . (yet) it can. (Choice C is unclear.)
940 MCQ for effective preparation of the test of Usage of English Grammar section.
Read the MCQ statement: Insomnia does not usually begin as a physical problem. It can affect one's physical health. , keenly and apply the method you have learn through the video lessons for Usage to give the answer. Record your answer and check its correct answer and video explanation for MCQ No. 298-4577.