HORTICULTURE

Detailed explanation-1: -The plant hormone auxin is well known to stimulate cell elongation via increasing wall extensibility. Auxin participates in the regulation of cell wall properties by inducing wall loosening.

Detailed explanation-2: -Auxins are known primarily for their ability to induce cell elongation. In addition, they stimulate cell division, vascular differentiation, and root initiation.

Detailed explanation-3: -Conclusions: The results indicate that auxin regulates the level of H2O2 in the root tip, so increasing the auxin level triggers accumulation of H2O2 leading to inhibition of root cell elongation and root growth.

Detailed explanation-4: -The process of parthenocarpy is induced by auxin. Auxin has characteristics similar to morphogens. Therefore, all of the functions of auxin mentioned in the above options are used in wide applications. So, option D is the correct option.