Which of the following are plant growth promoters?

Correct option is A. NAA, IBA, Zeatin,GA3
Plant hormones are signal molecules produced within plants, that occur in extremely low concentrations.
Plant Growth Promoters are substances which improve the overall healthy growth and development of plants.These substances may be either synthetically produced or obtained from Biological derivatives.
There are five major hormones which are auxin, cytokinin, gibberellin, abscisic acid, and ethylene.
Each hormone differs in its effects. The auxins(NAA, IBA), gibberellins(GA3), and cytokinins(Zeatin) act as growth stimulators, whereas, abscisic acid and ethylene act as growth inhibitors.
Hence, NAA, IBA, Zeatin, GA3 are plant growth promoters.
So, the correct answer is 'NAA, IBA, Zeatin, GA3'.