Which of the following is NOT a waste product of plants?

Auxins is not a waste product of plants. Auxins are a type of plant hormone that regulates various aspects of plant growth and development, such as stem elongation, root growth, and tropisms (movement in response to stimuli like light or gravity). On the other hand, gum, resins, and tannins are all waste products of plants. Gum is a sticky substance that is produced by some plants as a way to seal wounds or protect themselves from pathogens. Resins are produced by many types of trees as a way to protect themselves from insects and other pests, and also to seal wounds. Tannins are a type of chemical compound that is produced by plants as a defense against herbivores, and can also be used to help protect the plant from fungal and bacterial infections. So in summary, auxins are not a waste product of plants but rather an important plant hormone that plays a key role in regulating various aspects of plant growth and development.