## **Core Concept**
The question tests knowledge of the innate immune mechanisms, specifically the antimicrobial substances present in human tears. Tears contain several components that help protect the eyes from infections. One key substance is an enzyme that has antibacterial properties.

## **Why the Correct Answer is Right**
The correct answer, **Lysozyme**, is an enzyme found in tears, saliva, and other bodily secretions that has antimicrobial properties. Lysozyme works by breaking down the peptidoglycans in bacterial cell walls, ultimately leading to the destruction of the bacteria. This mechanism is crucial for the innate immune response, providing immediate protection against infections.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is blank and does not provide a substance, making it incorrect by default.
- **Option B:** This option is also blank and does not offer a valid substance, making it incorrect.
- **Option C:** Similarly, this option is blank and lacks a substance, which makes it an incorrect choice.
- **Option D:** This option is blank as well and does not present a valid antimicrobial substance found in tears.

## **Clinical Pearl / High-Yield Fact**
A memorable point for exams is that lysozyme is notably present in high concentrations in tears and plays a significant role in protecting the eyes from bacterial infections. This is a classic example of the body's innate immune mechanisms.

## **Correct Answer Line**
**Correct Answer: B. Lysozyme**