Glands and muscles are activated by:

Explanation

Option A: Sensory neurons transmit information from the environment to the central nervous system (CNS). Option B: Associative neurons integrate information from sensory neurons and send signals to motor neurons. Option C: Relay neurons transmit signals from one part of the CNS to another. Option D: Motor neurons activate glands and muscles. Motor neurons are the final pathway in the nervous system that controls the contraction of muscles and the secretion of glands. They receive signals from associative neurons and send signals to the muscles and glands. The signals from motor neurons are called motor impulses. Motor impulses cause muscles to contract and glands to secrete.