A researcher working in the field of evolution has decided that they would like to develop a species of pig that can fly. Out of the following issues, what is the biggest one that will impede the progress of this project?

A) Most pig species require lots of resources to maintain , making it difficult to care for the animals.

B) Pig genomes have many active retroviral elements in the genome that introduce many mutations every generation

. C) There are no pig species that have individuals with any characteristics that we associate with flight .

D) Designing an environment that would select for pigs that could fly or select against pigs that could not fly .