What prevents a monopolistic competition from being perfectly competitive?

Question

A. Consumers are not knowledgeable.
B. The market is dominated by one firm.
C. Products are not identical.
D. The barriers to entry are significant.
Is it A?

Answer 1

No.

https://www.investopedia.com/ask/answers/040915/what-difference-between-monopolistic-market-and-perfect-competition.asp

Answer 2

So the answer is C.

Answer 3

Is that what you learned from the Investopedia article?

Answer 4

Yes.

Answer 5

Then it must be the right answer.