What do auxin, cytokinin, and gibberellin have in common?

Auxin, cytokinin, and gibberellin are all classified as plant growth hormones, which means they play vital roles in regulating various aspects of plant growth and development. Each of these hormones has specific functions that contribute to processes like cell elongation, division, and differentiation. For example, auxin is primarily involved in the elongation of plant cells, which facilitates processes like phototropism and gravitropism. Cytokinins promote cell division and can influence the growth of roots and shoots, while gibberellins are crucial for processes such as seed germination, stem elongation, and flowering.

Together, these hormones interact with each other and with other signaling pathways to ensure that plants grow and develop in response to their environment and internal developmental cues. Their commonality as plant growth hormones highlights their importance in plant physiology, making option A the correct choice.