Which chemical acts as an aid for mechanical harvesting?

Correct option is C

ABA (Abscisic acid) is the chemical that acts as an aid for mechanical harvesting.
Abscisic acid (ABA) is a key hormone involved in tuning responses to several abiotic stresses and also has remarkable impacts on plant defense against various pathogens.
It acts as plant growth regulator, especially in seed maturation, seed dormancy, adaptive responsive to biotic and abiotic stresses and leaf and bud absicission.