Answer: Option B.
Genetic drift.
Explanation:
Adaptive radiation is the fat evolution of several species from a common ancestors, when a change in environment make available new resources or create new opportunities. It is characterized by ecological and morphological diversity. The factors or conditions that lead to adaptive radiation are colonization of an isolated that contain suitable habitat and few competitors species, evolutionary innovation,adaptive radiation in a group of organisms that another group use as food and vacant ecological niches.
Genetic drift is not a direct consequence factor of adaptive radiation.
Genetic drift is a process that occur in small population which is due to change in allele frequencies of a population due to certain occurrences. In this case few of the population can separate from the entire or the whole population is reduced, hence it is not a direct consequences of adaptive radiation.