I thought it was (d) but I might be wrong
Chordates (phylum Chordata) are animals which are either vertebrates or one of several closely related invertebrates. They are united by having, for at least some period of their life cycle, a notochord, a HOLLOW DORSAL NERVE CORD
Explanation:
Amino acid is made of an Amino group , a Carboxyl group And an R group . there is also an additional H there .