Answer :
Final answer:
A reservoir is the natural habitat where a pathogen exists, which can be in living organisms or in the environment like soil and water. Option a is the answer.
Explanation:
The best definition of a reservoir is the habitat in which a microbe naturally lives, grows, and multiplies. Reservoirs can be living organisms such as humans, animals, and plants or nonliving sites including soil and water. These reservoirs maintain the pathogen before and after infection. Diseases can be spread from these reservoirs to humans directly, such as in the case of zoonotic diseases like rabies and salmonellosis, or indirectly through contamination, as seen with pathogens causing Legionnaires' disease.
In summary, the correct answer to the student's question is:
- a. The place where a pathogen naturally exists.