The leaf defoliator utilized in the Vietnam war by the USA known as “Agent Orange” was

The correct option is 2,4, -D and 2,4,5 – T.

Explanation:
Agent Orange was a powerful mixture of synthetic herbicides and defoliants used extensively by the U.S. military during the Vietnam War as part of its herbicidal warfare program, Operation Ranch Hand.
The primary objective of using Agent Orange was to defoliate forested and rural land, depriving guerrilla fighters of cover and destroying crops to disrupt their food supply.

The chemical composition of Agent Orange consisted of equal parts of two distinct synthetic auxins (herbicides):
1. 2,4-D (2,4-Dichlorophenoxyacetic acid)
2. 2,4,5-T (2,4,5-Trichlorophenoxyacetic acid)

These substances mimic natural plant growth hormones (auxins), causing rapid, uncontrolled growth in broadleaf plants, which ultimately leads to defoliation and death of the plant. Therefore, the combination of 2,4-D and 2,4,5-T is what defined the defoliant Agent Orange.