While hiking in a tropical rainforest, you find a large, snakelike organism that is 1-meter-long, has smooth skin, and appears to be segmented. You think it might be a snake or an amphibian. Which of the following characteristics, if observed, should help you arrive at a conclusive answer?
A) presence of moist, highly vascularized skin
B) presence of scales
C) presence of a nerve cord
D) presence of a digestive system with two openings