Answer:
The correct answer would be immunisation.
Immunisation refers to the process of developing immunity against a particular pathogen or disease.
In this process, a vaccine consists of attenuated or heat killed pathogen is administered into a person.
The body produces a primary immune response against the weakened pathogen or antigen. It also develops memory of the pathogen due to which body is able to recognise the pathogen easily if it encounters the same in near future.
It helps the immune system to produce quicker and amplified immune response against the pathogen and our body becomes immune to that particular disease or pathogen.
Thus, immunisation is required before travelling to Africa as yellow fever is very common there.
