Name the organs of respiration in the following organisms:
$(a)$ Flatworm
$(b)$ Birds
$(c)$ Frog
$(d)$ Cockroach

(N/A) Flatworm: Respiration occurs through the general body surface via diffusion.
$(b)$ Birds: Respiration occurs through a pair of lungs.
$(c)$ Frog: Respiration occurs through moist skin (cutaneous respiration),oral cavity,and lungs (pulmonary respiration).
$(d)$ Cockroach: Respiration occurs through a network of tubes called the tracheal system.