A Carbon Skeleton Is Covalently Bonded to Both an Amino

A carbon skeleton is covalently bonded to both an amino group and a carboxyl group. When placed in water it

A) would function only as an acid because of the carboxyl group.
B) would function only as a base because of the amino group.
C) would function as neither an acid nor a base.
D) would function as both an acid and a base.
E) is impossible to determine how it would function.