11. Respiration occurs
A. independent of cellular activity.
OB. on the internal level only.
C. externally and internally.
OD. on the external level only.

Respiration occurs externally and internally.

Explanation:

Respiration is the metabolic process of converting  the energy stored in biological molecules to usable energy inform of ATP.  Respiration can be categories into three types; internal, external and cellular respiration.

EXTERNAL  RESPIRATION

this is the process which involves breathing in (inhalation) and breathing out (exhalation) of gases.

INTERNAL RESPIRATION

When gases are exchanged between blood and body cells its said to be  external respiration.

CELLULAR RESPIRATION

This involves the process by which food gets converted to energy and this is either aerobically ( needs oxygen) or anaerobically ( does not require energy.