Which of the following hormones is responsible for root growth and cell division?

The hormone responsible for root growth and cell division is auxins. Auxins are a class of plant hormones that play a key role in various growth processes, particularly in the elongation of cells and the development of roots. They promote the formation of roots from cuttings and are involved in the regulation of cell division and extension, which supports overall plant growth and structure.

Gibberellins, which were chosen as the answer, are indeed important hormones but are primarily known for their role in promoting stem elongation, germination of seeds, and flowering. They are less directly associated with root growth compared to auxins.

Ethylene is a gaseous hormone typically involved in processes like fruit ripening and the response to stress rather than in root growth.

Abscisic acid is known for its role in promoting seed dormancy and closing stomata during drought conditions, thus not directly contributing to root growth or cell division.

In contrast, auxins play a direct and significant role in encouraging these processes, making them the correct answer for this question.