Q: Fact 1: The moon revolving around the Earth causes the phases of the moon. Fact 2: Tides also calculates the moon phases and the tide's coefficients. Given the two facts above, what can the moon revolving around the earth be used to calculate?

Available options: (a). seasons; (b). pain; (c). magnetism; (d). tides; (e). voltage; (f). Length; (g). weight; (h). motion;
The answer is:
(d).