**Core Concept**
Diphtheria is a bacterial infection caused by Corynebacterium diphtheriae, characterized by the production of a toxin that leads to local tissue damage and systemic complications. The toxin, diphtheria toxin, is produced by the bacteria and causes the characteristic membrane formation in the throat.

**Why the Correct Answer is Right**
The correct answer is related to the mechanism of diphtheria toxin production. Corynebacterium diphtheriae produces the diphtheria toxin due to the expression of the tox gene, which is regulated by the gene product of the toxR gene. The toxin then causes the formation of the membrane in the throat by damaging the epithelial cells and leading to the accumulation of fibrinogen and other proteins. This membrane can lead to respiratory obstruction and other complications if left untreated.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not accurately describe the pathogenesis of diphtheria.
**Option B:** This option is incorrect as it does not mention the role of the tox gene in diphtheria toxin production.
**Option C:** This option is incorrect as it does not accurately describe the membrane formation in diphtheria.

**Clinical Pearl / High-Yield Fact**
The diphtheria toxin is a potent inhibitor of protein synthesis, and its production is regulated by the toxR gene. This is an important mechanism to remember when considering the pathogenesis of diphtheria.

**Correct Answer:** D.