Which dermatomes are responsible for innervating the diaphragm?

The diaphragm, a crucial muscle for respiration, is primarily innervated by the phrenic nerve, which arises from the cervical plexus. Specifically, the nerve roots responsible for this are those at the levels of C3, C4, and C5. These nerve roots contribute to the formation of the phrenic nerve, enabling motor control of the diaphragm as well as some sensory innervation. The phrase often used to remember this is "C3, C4, and C5 keeps the diaphragm alive," highlighting their critical role in diaphragmatic function and thus in the process of breathing.

The other choices represent different areas of innervation that do not influence the diaphragm directly. Hence, the involvement of C3, C4, and C5 in the innervation of the diaphragm clearly establishes this as the correct answer.