Correct Answer (Detailed Explanation is Below)
B.
Abscisic acid
Detailed Explanation
Abscisic acid (ABA) plays an important role in stomatal closure during water stress. When plants experience drought, ABA signalling causes changes in guard-cell ion and water balance, promoting closure of stomata and reducing water loss. Important plant hormones for examinations include
auxin, gibberellin, cytokinin, ethylene and ABA.