Is the answer C?

Added the OA. It was there before that we have had problems with the tags.

Regards

People whose bodies cannot produce the substance cytochrome P450 are three times as likely to develop Parkinson's disease, a disease that affects the brain, as are people whose bodies do produce this substance. Since cytochrome P450 protects the brain from toxic chemicals, toxic chemicals probably play a role in the development of Parkinson's disease.

Which of the following, if true, most strongly supports the argument？

(A)It will soon be possible for cytochrome P450 to be synthesised for the treatment of people whose bodies cannot produce this substance.

We do not have any suggestion of this in the passage.

(B)Many people whose bodies are unable to produce cytochrome P450 lack the ability to produce certain other substances as well.

There is no mention of any other substance in the stimulus besides P450

(C)Cytochrome P450 has no effect on the brain other than to protect it from toxic chemicals.

Clearly the logic implies that Parkinson's is PROBABLY caused due to the lack of protection from toxic chemicals and stating that the absence of P450 from the brain allows toxic chemicals to affect it means that the primary function of P450 to protect against toxins and therefore is strengthening the conclusion that toxins play a role in the development of Parkinson's.

(D)People with Parkinson's disease often exhibit a marked lessening in the severity of their symp- toms when they are treated with dopamine, a chemical produced naturally in the brain.

There is no connection between P450 and dopamine displayed in the passage.

(E)Many people with Parkinson's disease have the ability to produce cytochrome P450 naturally.

We already know this from the passage, a strengthening statement is usually not repeated in the passage.