**Core Concept**
Reversible pulpitis refers to a mild, temporary inflammation of the dental pulp, usually caused by thermal, chemical, or mechanical stimuli. This condition is characterized by a brief, self-limiting response of the pulp to an irritant, without causing permanent damage to the pulp or tooth.

**Why the Correct Answer is Right**
The correct answer is a type of pulpitis that is typically seen in response to irritants such as hot or cold substances, or sharp tooth decay. The pulp's response is mediated by the release of chemical mediators, including histamine, bradykinin, and prostaglandins, which cause vasodilation, increased permeability, and pain. The pulp's blood supply and defense mechanisms can usually counteract these effects, leading to resolution of the inflammation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe a specific type of pulpitis.
**Option B:** This option is incorrect because it is a more severe form of pulpitis that can lead to necrosis and permanent damage to the pulp and tooth.
**Option C:** This option is incorrect because it is a term used to describe a type of pulpitis that is not reversible.

**Clinical Pearl / High-Yield Fact**
A mnemonic to remember the causes of reversible pulpitis is "HEAT": Hot, Extreme, Acidic, and Thermal stimuli can all cause reversible pulpitis.

**Correct Answer: D. Tenderness to percussion.**