Which of the following is produced during water stress and causes closure of stomata?

Answer: Option A

Abscisic acid is produced during water stress and causes the closure of stomata.
Abscisic acid (ABA) is a plant hormone involved in the response of plants to reduced water availability.
Reduction of guard cell turgor by ABA diminishes the aperture of the stomatal pore and thereby contributes to the ability of the plant to conserve water during periods of drought.