M. S. Swaminathan was:

Concept

A person's professional classification is based on the field in which they trained and made their principal contributions. Agricultural scientists apply genetics, plant breeding, and related sciences to improve crops and food security.

Application

M. S. Swaminathan was an Indian agricultural scientist and geneticist. His work on high-yielding wheat and rice varieties helped advance India's Green Revolution.

Contrast

• Journalists collect, verify, and report news; that was not Swaminathan's principal profession.

• Ecologists study relationships between organisms and their environments; this label does not describe his main professional field.

• Ornithologists specialize in the scientific study of birds; that was not his field.

Therefore, M. S. Swaminathan was an agricultural scientist.