Which Statement Concerning Receptors Is Correct

Multiple Choice

Which statement concerning receptors is correct?

A) They are present for every modality in the environment.
B) When stimulated, they bring about opening of K⁺ channels in the efferent neuron membrane.
C) Mechanical receptors are sensitive to varying amounts of heat.
D) They may be either a specialized ending of an afferent neuron or a special cell closely associated with the peripheral ending of an afferent neuron.