Resistance of population to a pathogen as a result of immunity of a large portion of the population is known as:

Correct option is D

Explanation:
Herd immunity occurs when a significant portion of a population becomes immune to a disease, making the spread of the disease from person to person unlikely. As a result, the whole community is protected — not just those who are immune.
Information Booster:
Herd immunity can be achieved through:
· Vaccination, which is the safest method.
· Natural infection, though this comes with higher risks.
The threshold for herd immunity varies depending on the disease — for example, it is about 83–94% for measles.
Additional Knowledge:
· Innate immunity: The natural defenses we are born with (e.g., skin, mucous).
· Adaptive immunity: Acquired immunity through exposure to pathogens or vaccines.
· Morbidity: Refers to the presence of illness or disease in a population.