Moving molecules across the cell membrane.

• A. Cell Transport Mechanism
• B. Diffusion
• C. Osmosis
• D. Active Transport

Answer: (A)

Moving molecules across the cell membrane is described by cell transport mechanisms. This umbrella term covers all the ways substances cross the membrane, including passive processes like diffusion and osmosis, as well as active processes that require energy. Diffusion is the movement from high to low concentration without energy, osmosis is the diffusion of water specifically through a semipermeable membrane, and active transport uses energy to move substances against their gradient. Since the question points to the overall process of crossing the membrane, the broad term that includes all these methods best fits.