Hi all, can somebody explain why answer choice (c) is incorrect?

I thought it was a good choice for the following reason:

(C) Whenever most practitioners of a given discipline (the psychologists) approach a particular problem in the same way (should the childhood age group be understood in its own terms), that uniformity is good evidence that all similar problems (should the elderly age group be understood in its own terms) should be approached in that way (yes, it should be understood in its own terms, just like psychologists do for children)

Please, if you can let me know where I’m wrong that’ll be greatly appreciated.

Thank you,