**Explanation:**

The correct answer is option "B" - Antibodies.

Measles is a highly contagious viral infection that primarily affects children. It spreads through respiratory droplets from an infected person, and its symptoms include high fever, cough, runny nose, red eyes, and a characteristic rash.

To prevent measles, the most effective method is vaccination. The measles vaccine is part of the routine childhood immunization schedule and is typically administered in combination with mumps and rubella vaccines (MMR vaccine) or with mumps, rubella, and varicella vaccines (MMRV vaccine). Vaccination provides long-term immunity against measles and helps to prevent its transmission within the community.

Here is a breakdown of the given options and why they are or are not included in the prevention of measles:

a) Vaccination:
- Vaccination is a crucial component in the prevention of measles.
- The measles vaccine stimulates the body's immune system to produce specific antibodies against the measles virus.
- These antibodies provide immunity, preventing the person from getting infected or reducing the severity of the disease if they do get infected.
- Vaccination not only protects the individual but also helps to create herd immunity, where a large portion of the population is immune and reduces the overall transmission of the virus.

b) Antibodies:
- Antibodies are produced by the immune system in response to an infection or vaccination.
- While antibodies play a critical role in fighting off infections, they are not a method of preventing measles on their own.
- Antibodies are produced in response to the presence of the measles virus or the introduction of the measles vaccine.
- They help the immune system recognize and neutralize the virus, but they do not prevent the initial infection.
- Antibodies are a part of the immune response, but they are not a standalone prevention method.

c) Both A and B:
- This option is incorrect because vaccination is a valid method of preventing measles, and antibodies are a natural immune response but not a preventive measure on their own.

d) None of these:
- This option is incorrect because vaccination is a proven and effective method of preventing measles.

In conclusion, the prevention of measles primarily relies on vaccination, which stimulates the production of antibodies. While antibodies are essential in fighting off the infection, they are not a direct preventive measure on their own.