Answer the following question: Fact 1: When the season changes , the amount of daylight will change. Fact 2: The tilt of Earth's axis accounts for why there are seasonal changes in (a) the hours of daylight and (b) the intensity of solar radiation at any location on Earth. Given the two facts above, that there are seasons on Earth is partly due to: ?

Choose from:
1). the Earth being tilted;
2). mixing of air between the north and south hemispheres;
3). seasonal variation of rotation speed;
4). mechanical motion;
5). Changes in distance between the Earth and Sun;
6). Something that makes plants green;
7). Earth's axis of rotation is tilted;
8). Continents drifting;
Answer:
7).