Which researcher(s)are using a metagenomic approach?

A) A medical researcher studies the DNA of mixed bacterial populations from the intestines of patients with different diseases.
B) A plant biologist sequences the genomes of broccoli, cauliflower, and other Brassica species to determine which genes are responsible for their different features.
C) A developmental geneticist clones the mutated gene from a Drosophila strain with disrupted wing development.
D) An environmental researcher sequences DNA from collections of microbes living in polluted coastal waters, which cannot be cultured in the lab.
E) A pharmaceutical developer screens through DNA found in soil samples for novel antibiotics.