Phasic receptors Phasic receptors slowly decrease the frequency of action potentials generated to a constant stimulus. detect parameters that the body must continuously assess. once threshold is reached by a stimulus will always generate action potentials. are quick to adapt to a constant stimulus.

Option D, are quick to adapt to a constant stimulus.

Explanation:

Phasic receptors are very essential for quickly adapt a constant stimulus and determine the changes such as velocity, acceleration etc. in it. It does not provide information regarding the position of stimulus just like a tonic receptor. However, it provide  information regarding the intensity &  rate of change of stimulus and the ups and down of the frequency  of  discharge of nerve impulse.  

Hence, option D is correct