Plant hormones play a crucial role in regulating various physiological processes in plants, including growth, development, and response to environmental stimuli. There are several types of plant hormones, and some of the most important ones include auxins, cytokinins, and gibberellins.

Auxins:
- Auxins are a class of plant hormones that are primarily involved in promoting cell elongation, root initiation, and apical dominance.
- They also play a role in phototropism and gravitropism, helping plants grow towards light and in the right direction.

Cytokinins:
- Cytokinins are plant hormones that are known for their role in promoting cell division and differentiation.
- They are involved in various processes such as leaf senescence, root development, and nutrient mobilization.

Gibberellins:
- Gibberellins are plant hormones that regulate various growth processes, including stem elongation, seed germination, and flowering.
- They also play a role in breaking seed dormancy and promoting fruit growth.

All of the above:
- All three of these hormones, auxins, cytokinins, and gibberellins, are essential for plant growth and development.
- They work together in a complex network to regulate various physiological processes and ensure that the plant responds appropriately to its environment.
In conclusion, plant hormones are crucial for the proper growth and development of plants, and auxins, cytokinins, and gibberellins are some of the key players in this regulatory network.