Final answer:
A gated channel responds to specific stimuli and will remain closed if unstimulated. The stimuli that trigger opening can vary, such as chemical signals or physical distortions, and after activation, these channels can become temporarily inactivated.
Step-by-step explanation:
The behavior of a gated channel can best be described as a membrane protein that opens in response to specific stimuli. When stimulated, a gated channel such as a voltage-gated ion channel will open and allow ions like Na+ to pass through the membrane, and after activation, they become inactivated for a brief period, during which they cannot be reopened by a stimulus. The stimuli that cause these gates to open can vary based on the type of gated channel and include chemical signals like the binding of a neurotransmitter, changes in membrane voltage, temperature changes, or physical deformation as seen in mechanically gated channels.
For instance, the activation gate of a sodium voltage-gated channel opens when the membrane potential reaches a certain threshold, while the inactivation gate closes shortly thereafter to prevent further ion influx. As a result, these channels exhibit complex behaviors depending on the type of stimulus they are designed to respond to and do not simply open more widely or remain open continuously. Therefore, they remain closed if unstimulated, which is option d).