Most widely used compound as a source of ethylene is

Ethylene is a

Which of the following induces sprouting of potato tubers?

The only gaseous plant hormone is . . . . . . .

Which hormone is produced mostly in all parts of a plant?

$I.$ More female flowers in cucumber
$II.$ $\alpha$-amylase production in barley grain
$III.$ Acceleration of fruit ripening in tomato
$IV.$ Delay in sprouting in potato tubers
From the given effects,identify the effects of ethylene and choose the correct option accordingly.