Correct Answer - D
Kogl et al. (1931) isolated auxin from human urine called heteroauxin which was identified as indole-3-acetic acid (I A A). Zeatin is a cytokinin-like substance isolated and crystallised by Letham (1963-65) from milky endosperm of corn (Zea mays). It also occurs in coconut milk.
Yabuta and Sumiki (1938) isolated a chemical substance from the cultural filtrate of fungus Gibberella fujikurol in crystalline form and named it gibberellic acid.
Cousins (1910) found that ripe oranges produced a volatile substance that hastened ripening of unriped bananas nearby. with the help of gas chromatography, R. Gane (1934) found that the ripening causing volatile substance was ethylene.
