Answer: Smallpox
Explanation: Small pox is an ancient disease which is caused by the Virus named as Variola virus. Early symptoms are fatigue and high fever.
The virus then after produces rash on faces arms and legs. The spots gets filled with fluid and pus and in later stages it turned into crust.
This crust eventually dried and falls off. It was fatal in almost 30% of the cases.
It eradicated by a collaborative global vaccination program which was led by WHO.
Natural selection refers to the phenomenon by which the species in a population possessing the tendency to get adapted in a condition enhance in numbers in comparison to those who exhibit fewer adaptation capacities over a number of generations.
In other words, it can be stated as the non-random and differential development of distinct genotypes function to sustain favorable variant and to eradicate less favorable variants. Some of the conditions are required for the process of natural selection to take place.
These are heredity, reproduction, variation in individual characters, and variation in the fitness of organisms among the members of the population. If the conditions are met, then the phenomenon of natural selection occurs by default.
I believe the answer is B
