Agent, host and ............. make it a epidemiological triad.

Correct option is C

Sol. The epidemiological triad consists of agent, host, and environment. This model explains the cause and spread of diseases by analyzing how these three factors interact.
Explanation of each option:
· (a) Immunity – This is a host factor affecting susceptibility but not a core component of the triad model.
· (b) Susceptibility – This again is a host characteristic, not a separate element in the triad.
· (c) Environment – Correct answer. The environment influences how disease agents reach hosts and can promote or hinder disease spread.
· (d) Medicines – These are interventions used for treatment or prevention, not part of the foundational epidemiological model.