The modern model of the Plate Tectonic Theory suggests that the continents and the major tectonic plates drift slowly on —

the upper layer of the Earth's mantle

Explanation:

Not the ocean, impossible to be in top of the core, not in the air

the upper layer of the Earth's mantle

small, big, or no change could occur in the phenotype. it could cause something as simple as a cats ears to curl backwards or something as frighting as death. it could also occur in the protien-coding area and have an effect on that but no effect on the amino acids. what has to occur is a changing in the hox gene or the control gene.

i believe your answer would be c.. : )