One of the synthetic auxin is
a)	NAA	b)	IAA	c)	GA	d)	IBA

(a)

The term ‘auxin’ is applied to the indole-3-acetic acid (IAA) and to other natural and synthetic compounds having certain growth regulating properties. NAA Naphthalane Acetic Acid (NAA) and 2,4-D (2,4-dichlorophenoxyacetic acid) have been isolated from plants. All these auxins have been used extensively in agricultural and horticultural practices.