13. Why has C. elegans proven to be a useful model for understanding apoptosis? (A) C. elegans does not naturally use apoptosis, but can be induced to do so in the laboratory. (B) C. elegans undergoes a fixed and easy-to-visualize number of apoptotic events during its normal development. (C) C. elegans has large cells wherein apoptosis is easily observed without the aid of a microscope. (D) As C. elegans ages, its cells die progressively until the whole organism is dead.