Final answer:
Gated channels can be opened or closed by mechanical forces, voltage differences, or binding of a ligand, but not by voltage clamping.
Step-by-step explanation:
Gated ion channels can be opened or closed by mechanical forces, voltage differences, or binding of a ligand. However, they cannot be opened or closed by voltage clamping.
Mechanically-gated channels open in response to physical distortions of the cell membrane, such as pressure or temperature changes. Voltage-gated channels require a change in voltage across the membrane to open. Ligand-gated channels open when a specific molecule or ion binds to the channel protein.
Therefore, the correct answer is option d: voltage clamping does not cause opening or closing of channels.