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प्रश्न
The bending of the stem of a plant towards a source of light is caused by the action of a phytohormone known as :
(a) abscisic acid
(b) auxin
(c) gibberellins
(d) cytokinin
उत्तर
(b) auxin
Auxin causes phototropism, i.e., bending of plant stems towards the source of light.
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