ABA is involved in _________. Increased cell division, shoot elongation, dormancy of seed, root elongation.

ABA is an abscisic acid or stress hormone that induces dormancy in buds, promotes abscission of flowers and fruits, decreases transpiration losses, stops protein and RNA synthesis in leaves, promoted rooting in stem cutting promotes development, and maturation of seed, and inhibit seed germination, etc. Hence, the correct answer is option C, i.e., Dormancy of seed.