What process causes plate tectonics? A. Conduction currents in the mantle
B. Radiation in Earth's core
C. Reversed polarity across the ocean bottom
D. Convection currents in the mantle

It's b,

Explanation:

The process of plate tectonics may be driven by convection in Earth's mantle, the pull of heavy old pieces of crust into the mantle, or some combination of both. For a deeper discussion of plate-driving mechanisms, see Plate-driving mechanisms and the role of the mantle.

the answer for this question would be d. glaciers