Explanation:

A – II, B – IV, C – I, D – III

Chlorophyll a contains a magnesium ion encased in a large ring structure known as a chlorin. The chlorin ring is a heterocyclic compound derived from pyrrole. Four nitrogen atoms from the chlorin surround and bind the magnesium atom. The magnesium center uniquely defines the structure as a chlorophyll molecule

IAA (Indole-3-Acetic Acid) is the abundant and well known plant hormone of the auxin class. IAA is predominantly produced in the apical bud of and young leaves of plants and is known to be an inducer of cell division and elongation.

Nitrate reductases are molybdoenzymes that reduce nitrate (NO − 3) to nitrite (NO − ). This reaction is critical for the production of protein in most crop plants, as nitrate is the predominant source of nitrogen in fertilized soils