Final answer:
Option E, Na+ channel inactivation or K+ channel opening, is responsible for a receptor adapting to a stimulus.
Step-by-step explanation:
The response to this question is option E, Na+ channel inactivation or K+ channel opening, which means that both Na+ channel inactivation and K+ channel opening are responsible for a receptor adapting to a stimulus.
When a stimulus is received, Na+ channels open, allowing Na+ ions to enter the cell and depolarize the membrane. However, over time, the Na+ channels become inactivated, preventing further Na+ entry. At the same time, K+ channels open, allowing K+ ions to leave the cell and help repolarize the membrane.
Therefore, both the inactivation of Na+ channels and the opening of K+ channels play a role in allowing the receptor to adapt to a stimulus.