**Core Concept**
The concept of a carrier in infectious disease refers to an individual who harbors a pathogen, such as a bacterium, virus, or parasite, and can transmit it to others without necessarily displaying symptoms themselves. This individual serves as a reservoir for the pathogen, allowing it to spread within a population.

**Why the Correct Answer is Right**
A carrier is typically defined as someone who is infected with a pathogen but does not exhibit any clinical symptoms of the disease. This can be due to various factors, such as the host's immune response, the pathogen's virulence, or the presence of asymptomatic carriers. In many cases, carriers can transmit the pathogen to others through respiratory droplets, direct contact, or contaminated food and water. The presence of carriers highlights the importance of public health measures, such as vaccination, sanitation, and contact tracing, to prevent the spread of infectious diseases.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not accurately describe the definition of a carrier. A carrier is not necessarily someone who is immunized against a disease.
* **Option B:** This option is incorrect because it is not a clear definition of a carrier. A person with latent infection may not be considered a carrier in the classical sense.
* **Option C:** This option is incorrect because it is a definition of a reservoir, not a carrier. A reservoir refers to an individual or environment that harbors a pathogen, but does not necessarily transmit it to others.

**Clinical Pearl / High-Yield Fact**
It is essential to distinguish between carriers and individuals with latent infections, as carriers can transmit pathogens to others, while those with latent infections may not be contagious.

**Correct Answer:** C.

✓ Correct Answer: C. Infected person harboring infectious agent without clinical features and acts as source of infection