A. an amino group B. a methyl group C. a phosphate group D. a carbonyl group

Answer: B. a methyl group
Explanation:
A methyl group is a functional group formed from methane having one carbon atom bonded to three hydrogen atoms. It is created by removing one of the hydrogen atoms from an atom of methane. Its molecular formula is CH3. It binds with other ions, such as OH, to produce chemical compounds.