On a map, the continents have shapes that almost fit together like pieces of a jigsaw puzzle. How does modern science explain this fit of the matching shapes in terms of processes inside Earth?

We explain this puzzle-piece-like build as proof of tectonic plate shifting. As magma inside the earth moves, so do the continental plates on top of the magma. The continents used to be fused together in one larger continent called Pangea. Over the course of 1000s of years, the plates have shifted.

tldr: tectonic plate movements cause this phenomena

I believe the answer is B, primary active transport. Root hair cells in plant use active transport to absorb mineral ions such as nitrates from the soil. The concentrations of minerals in the soil are lower in the soil than in within the root hair cell, therefore the transport will be against the concentration gradient which does not favor diffusion, therefore the pant has to use active transport.