**Core Concept**
A mosquito net's effectiveness in preventing mosquito bites is directly related to its mesh size, which is measured by the number of holes per square inch. The World Health Organization (WHO) recommends a mesh size of at least 150 holes per square inch to prevent mosquito bites.

**Why the Correct Answer is Right**
The correct mesh size of 150 holes per square inch is based on the idea that mosquitoes can pass through smaller openings. The mesh size should be small enough to prevent mosquitoes from entering, while still allowing air to pass through for ventilation. The WHO recommends this mesh size to prevent bites from mosquitoes that can transmit diseases such as malaria, dengue fever, and Zika virus.

**Why Each Wrong Option is Incorrect**
**Option A:** A mesh size of 50 holes per square inch is too small, allowing mosquitoes to pass through and negating the purpose of the net.
**Option B:** A mesh size of 200 holes per square inch is too large, providing inadequate protection against mosquitoes.
**Option C:** A mesh size of 100 holes per square inch is insufficient to prevent mosquito bites, as it allows mosquitoes to pass through.

**Clinical Pearl / High-Yield Fact**
When purchasing a mosquito net, look for one that meets the WHO's recommended mesh size of at least 150 holes per square inch to ensure effective protection against mosquito bites.

**Correct Answer:** C. 200 holes per square inch.