In some case, the brain can predict the stimuli and so start the interpretation already during the sensory perception, but in the usual case the stimuli have to first be perceived by the senses and only later can they be interpreted by the brain.
The chemoreceptor is a type of sensory receptor that detects and changes chemical material into biological signals. Generally, this receptor detects toxic chemicals in internal as well as from the external environment and sends the information to CNS. Generally, chemoreceptors are classified into two groups one is called distance chemoreceptors such as olfactory receptor neurons and the other is called direct chemoreceptors such as the taste receptor of the gustatory system.
the correct answer is d