Which of the following does not represent the possible structure of an acid? So if we take a look at the first one, we have HBR. This is a covalent compound with hydrogen at the beginning. It represents hydrochromic acid, so this is not an answer.
The next one is also covalent compound with a hydrogen in the beginning, so that's a dead giveaway that we have an acid. This one here is called iotic acid and then we have C&D. If we look at these two options, D is an acid because it is a covalent compound with a hydrogen at the beginning. Here this is called hypochlorous acid.
The answer is option C. We have C&H together. We don't have the hydrogen in the front so and it's covalent, but it doesn't have the hydrogen in the front. We said there are a few exceptions where hydrogen may not be in the front of the covalent compound such as acetic acid and positively charged amines. Here chapter port doesn't constitute one of those exceptions, so this would not represent a typical type of acid. So in this question the answer is letter C.