The application of synthetic plant hormones like IAA, IBA and NAA are best described as?
A) Prevent early fruit fall before harvesting and it's used to produce parthenocarpic fruit.
B) Prevent early fruit fall only
C) To produce both seedless fruits with seeds
D) To produce larger fruit

Hint: Synthetic plant hormones are the synthetic compounds that mimic the naturally occurring plant hormones. They function as growth regulators.

Complete Answer:
To solve this question, we must know the function of the growth regulators both naturally occurring and synthetic.
Naturally occurring plant growth hormones are called the auxins.It regulates various developmental processes in plants. Plant hormones and growth regulator are the chemicals which affect the flowering, aging, root growth, colour enhancement of fruit, prevention of leafing or leaf fall etc.
These hormones can be extracted by the plants naturally like IAA( Indoleacetic acid), IBA(Indolebutyric acid), or synthetically produced like NAA (Naphthalene acetic acid). NAA is widely used for agricultural purposes. It acts as a rooting agent. It is used in plant tissue culture. It is also used in vegetative propagation of plants from cuttings of leaf and stem.
It enhances fruit setting and helps in producing seedless fruits without fertilisation known as parthenocarpic fruit which are larger and sweeter.
For example seedless oranges are produced through this hormone. It also helps in early maturing of fruits and also prevents fruit fall before harvesting. Thus it is widely used for commercial purposes.

Thus, the correct answer is (A) Synthetic hormones prevent early fruit fall before harvesting and it is used to produce parthenocarpic fruit.

Note: Synthetic hormones are considered to be very toxic at higher doses. Higher doses can cause growth inhibition in plants. It can cause great toxicity to humans and animals when higher dosage is administered.