**Core Concept**
The question is testing the student's knowledge of the primary mode of transmission for certain infectious diseases. Specifically, it is inquiring about the role of mosquitoes as vectors for disease spread.

**Why the Correct Answer is Right**
Mosquitoes transmit various diseases to humans by injecting saliva or pathogen-containing saliva into the bloodstream during feeding. This process is facilitated by the mosquito's proboscis, which pierces the skin and allows the exchange of fluids. The most well-known examples of mosquito-borne diseases include malaria, dengue fever, Zika virus, and yellow fever. The primary vector responsible for spreading these diseases is the female mosquito, which requires a blood meal to lay eggs.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not specified and cannot be evaluated.
**Option B:** This option is not specified and cannot be evaluated.
**Option C:** This option is not specified and cannot be evaluated.

**Clinical Pearl / High-Yield Fact**
It's essential to note that not all mosquitoes transmit diseases. Only female mosquitoes of certain species, such as Anopheles and Aedes, are capable of transmitting pathogens to humans. This distinction is crucial for public health efforts aimed at preventing mosquito-borne illnesses.

**Correct Answer:** Malaria, dengue fever, Zika virus, and yellow fever are all spread by mosquitoes.