Available choices:
(1). it's state;
(2). voltage;
(3). wind;
(4). seasons;
(5). fever;
(6). Summer;
(7). sweating;
(8). sun's heat;
Q: Fact 1: Temperature falls from lower to higher altitudes. Fact 2: Temperatures vary with altitude and season. Given the two facts above, what makes temperature vary?
A:
(4).