Scientists theorized that the ice ages were caused by

changes in the tilt of the earth's axis

changes in the composition of gases that composed the earth's atmosphere

a slower movement of the earth in its orbit around the sun

a large fluctuation in temperature

ilankovitch cycles describe the collective effects of changes in the Earth's movements on its climate over thousands of years. The term is named for Serbian geophysicist and astronomer Milutin Milanković. In the 1920s, he hypothesized that variations in eccentricity, axial tilt, and precession of the Earth's orbit resulted in cyclical variation in the solar radiation reaching the Earth, and that this orbital forcing strongly influenced climatic patterns on Earth.

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Explanation:

the answer is b. apsidal precession

answer called a epicycle;