Answer:
D. Cytoskeleton
Step-by-step explanation:
It is really none of these answers. The correct answer would be a microtubule which is a component of the cytoskeleton which is in the cytoplasm.
The Cell Walls are only in plant cells so that won't work. So, A wouldn't work.
Chromosomes are the things that both your parents give you as genes. They have nothing to do with keeping the structure of the cell alright.
Cytoplasm cannot be a answer choice because, the thing is in it but, it doesn't do anything with it. So C wouldn't work either
The correct answer is microtubule however, it is a component of cytoskeleton so therefore, that is your answer.
Reference the picture below: