PL HEL Though some indications of frozen water have been found on Mars, and it can reach habitable temperatures in some places, no evidence of life has ever been found. Which of the following is most likely the reason Mars does NOT support life?
A. The composition of the atmosphere is not suitable for life.
B. The gravity on Mars is not strong enough to support life.
C. There is not enough sunlight to allow plants to grow.
D. The soil on Mars contains too many acidic salts.