The student would certainly observe all of those features. However having a nucleus would only say if it is an eukaryotic or a prokaryotic cell. Big vacuoles and chloroplasts are characteristics of plant cells, so the absence of them could help understand if it really is an animal cell. However, the easiest way to see in a microscope if it is not a plant cell, is to detect if there is a cell wall present. Cell walls are easier to observe as they are structures that surround the plasma membrane, and this is easier to detect by seing the cell under a microscope than organelles inside the cell that would have to be differentiated from other organelles (like vacuoles or chloroplasts).
Therefore, the correct answer is A. Does it have a cell wall?