Answer the question

The atmosphere of Mars is almost entirely composed of a greenhouse gas. Compared with Earth, which factor accounts for the low, nighttime surface temperatures on Mars?
Possible answers:
(I) Mars is much farther from the Sun than Earth.
(II) The atmosphere on Mars has an extremely low density.
(III) The atmosphere on Mars lacks global circulation.
(IV) Mars has more glacial activity than Earth.
(II)