Answer:
C) genetic drift.
Step-by-step explanation:
In this question, the alleles of the dominant trait that is without webbed feet are eliminated from the population due to flood in the area where the iguana population was living.
This elimination of the dominant alleles due to flood is a by chance event or a random event. This event changed the gene pool of the population and the population with left or recessive alleles will survive.
This change in the gene pool of a small population due to the random effect is known as the genetic drift.
Thus, Option-C is the correct answer.