Question

____ are in constant motion and change the forms of the earths crust.
a. solar flares
b. magnetic fields
c. tectonic plates
d. lunar phases

Explanation:

Tectonic plates are large sections of the Earth's crust. According to the theory of plate tectonics, these plates are in constant motion. Their movement (such as converging, diverging, or sliding past each other) leads to geological features like mountains (from convergent boundaries - plates colliding), ocean basins (from divergent boundaries - plates moving apart), and earthquakes (from transform boundaries - plates sliding past each other). Solar flares are eruptions on the Sun's surface, magnetic fields are related to magnetism around celestial bodies (like Earth's magnetic field), and lunar phases are the different appearances of the Moon as it orbits Earth. None of these (solar flares, magnetic fields, lunar phases) are directly responsible for changing the forms of the Earth's crust in the way described in the question.

Answer:

C. Tectonic plates