Q.Pathophysiology is the:

Pathophysiology is the study of how disease or injury alters the normal physiological processes of the body. It focuses on the changes in function that occur in the host as a result of a pathological condition, not on the pathogen itself or on normal, healthy physiology.

• Option (A) is incorrect because the study of the physiology of a pathogen is part of microbiology or virology, not pathophysiology.
• Option (B) is incorrect because the study of normal physiology is simply called physiology. …

To understand what pathophysiology means, you first need to break the word into its parts. "Patho-" comes from the Greek pathos, meaning suffering or disease. "Physiology" is the study of how the body normally works — how the heart pumps, how kidneys filter, how nerves transmit signals. So pathophysiology literally means the study of the body's functioning when it is disturbed by disease.

Think of it this way: normal physiology is like a well‑tuned engine running smoothly. Pathophysiology is what happens when a part fails — the engine sputters, overheats, or loses power. It is not the study of the failing part itself (that would be pathology, the study of structural changes), but rather the study of how the whole system responds to that failure.

Now look at the options carefully.

Option (A) says "Study of physiology of pathogen." That would be the study of how a disease‑causing microbe (like a bacterium or virus) functions — its metabolism, reproduction, etc. That is called microbial physiology or pathogen biology, not pathophysiology. So (A) is incorrect.

Option (B) says "Study of normal physiology of host." That is simply physiology — the study of healthy body function. Pathophysiology specifically deals with altered or abnormal function, so (B) is also wrong.

Option (C) says "Study of altered physiology of host." This is exactly right. When a person has diabetes, for example, the normal regulation of blood sugar is disrupted. Pathophysiology explains why blood sugar rises, how insulin resistance develops, and what consequences follow — all changes from the normal state.

Option (D) "None of the above" would only be correct if none of the first three matched, but since (C) is accurate, (D) is not the answer. …

Method — split the compound word

Patho- (disease) + physio- (function) + -logy (study of) = the study of function AS ALTERED BY disease. …