The phytohormone, which induces triple response growth is
a)	IAA	b)	ABA	c)		d)

(d)

It was a Russian Physiologist named Dimitry N Neljubow (1876-1926), who first established that ethylene affects plant growth. He identified ethylene in illuminating gas but showed that it causes a triple response on pea seedlings- inhibited stem elongation, increased stem thickening and a horizontal growth habit.