Hi There!
Question - Cells contain smaller parts known as organelles. The nucleus, chloroplasts, mitochondria, and vacuoles are all examples of organelles. What do these organelles have in common?
Answer - C. They are all enclosed by a membrane.
Why - The reason I say option C is the correct choice is because the fact that organelles are in membranes that contain lipids and proteins.
Hope This Helps :)