Question

by which mechanism would a steroid molecule diffuse into the cell?

Explanation:

Steroid molecules are lipid - soluble. They can pass through the lipid - bilayer of the cell membrane without the help of transport proteins. This is simple diffusion. Image A represents simple diffusion where molecules move directly through the lipid - bilayer from an area of higher concentration to an area of lower concentration. Image B shows facilitated diffusion which requires transport proteins, and Image C shows active transport which requires energy and transport proteins.

Answer:

A. Simple diffusion (represented by Image A)