Answer:
Ligand gated.
Explanation:
Channels are important as they help in the transferring of one molecule from one place to another inside the cells. These channels also provide the way of cell communication.
The ligand gated channels generally open in response to the binding of ligand or some molecules with the channel. Sodium gated channels open in response to the binding of sodium with the channels.
Thus, the correct answer is option (a).
