What causes a repeating pattern of day and night? A. The Earth rotates on its axis over 24 hours.
B. The Earth orbits, or revolves, around the sun.
C. The sun changes its position around the Earth.
D. The Earth is facing different parts of the sun as the day goes

A. The Earth rotates on its axis over 24 hours.

Explanation:

Day and night. The Earth is a sphere, or ball, which spins round and round as it travels around the sun. ... Because the Earth is constantly spinning, the line between day and night is always moving around the planet. A day on Earth lasts 24 hours—that is how long it takes for the planet to spin around once.

c-14 is carbon-14, or radiocarbon.   it is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons.