Which one of the following is the natural auxin?

🔑Key Points:
-IAA (Indole-3-Acetic Acid) is the abundant and well-known plant hormone of the auxin class.
-Its formula is C10H9NO2.
-IAA is predominantly produced in the apical bud of and young leaves of plants and is known to be an inducer of cell division and elongation.
-IAA, as well as most other auxins, are also known to act in concert with, or opposition to, other plant hormones.
-For example, the ratio of auxin to cytokinin in certain plant tissues determines the initiation of root versus shoot buds.

-NAA (1-Naphthaleneacetic acid) is a synthetic plant hormone in the auxin family.
-Its formula is C₁₀H₇CH₂CO₂H.
-A synthetic auxin (NAA) suppresses secondary wall cellulose synthesis and enhances elongation in cultured cotton fiber.
-4-D is a synthetic auxin, which is a class of plant growth regulators.
-It is absorbed through the leaves and is translocated to the meristems of the plant. Uncontrolled, unsustainable growth ensues causing stem curl-over, leaf withering, and eventual plant death.
-IBA (Indole-3-butyric acid) is a plant hormone belonging to the auxin family and assists in initiating root formation, the in vitro process is called micropropagation.
-Aside from accelerating root formation, it is used on various crops to stimulate flower development and the growth of fruits. This ultimately increases crop yields.
-Its formula is C12H13NO2.