Correct Option: A

The ovum is the largest cell in the human body, typically visible to the naked eye without the aid of a microscope or other magnification device. The smallest is the male sperm cell, it is one-tenth of the diameter of a human hair. Now, it is true that neurons can have very long extensions or axons, the axon isn’t a cell, but a peripheral extension. The actual neuron is tiny compared to the egg cell.