Answer:
Random chance mutations led to the webbed feet trait in ancestral land birds, conferring them an adaptive advantage. Birds that inherited the beneficial random mutations associated with the webbed feet trait had more chances to survive and reproduce, passing this trait to the next generations.
Explanation:
Mutations are ramdom changes in the nucleotide sequence of the genome of a particular organism. In general, mutations are deleterious, but mutations may occasionally be beneficial in certain environments. A beneficial mutation must be associated with one or more phenotypic traits capable of conferring an adaptive advantage in a certain environment, thereby the individuals carrying the mutation have more chances to reproduce and survive. In this case, one or more beneficial mutations associated with the webbed feet trait passed to the next generations, increasing their frequency in the population.
