Presence of this in the seed is linked with dormancy

The correct option is abscisic acid.

Seed dormancy is a physiological state in which viable seeds do not germinate even when placed under favorable environmental conditions, such as adequate moisture, temperature, and oxygen. This is an evolutionary adaptation that prevents seeds from germinating during unsuitable seasons, ensuring seedling survival.

The induction and maintenance of seed dormancy are tightly regulated by the balance of plant hormones (phytohormones). Among these, abscisic acid is the primary hormone responsible for promoting and maintaining seed dormancy. During the development and maturation of the seed, levels of abscisic acid rise, which prevents the embryo from germinating prematurely (a phenomenon known as vivipary) and keeps the seed in a dormant state until environmental cues trigger germination.

To further clarify, let us look at the functions of the other options:
1. Gibberellic acid: This hormone acts antagonistically to abscisic acid. Instead of promoting dormancy, gibberellic acid breaks dormancy and initiates germination by stimulating the synthesis of hydrolytic enzymes that digest stored food.
2. Starch: Starch is a storage polysaccharide that serves as a nutrient source for the embryo during germination. It does not act as a regulatory signal for dormancy.
3. Ethylene: Ethylene is a gaseous hormone involved in fruit ripening, senescence, and response to mechanical stress. It generally aids in breaking dormancy rather than inducing it.