Given below are four statements in respect of effects of plant growth regulators. Select the option that comprises the correct statements:
(1) Auxins promote shoot growth but at similar concentrations inhibit root growth.
(2) “Triple response” of dark-grown pea seedlings is a common bioassay of abscisic acid.
(3) Kinetin is not a natural plant growth regulator.
(4) TIBA is a gibberellin inhibitor.
Choose the correct answer from the codes given below:

Correct option is C

Correct Answer: (c)
Explanation:
Auxins at low concentration promote shoot elongation but inhibit root growth — Statement (1) is correct.
“Kinetin” is a synthetic cytokinin; the natural cytokinin is zeatin — Statement (3) is correct.
Triple response is a bioassay of ethylene, not ABA — Statement (2) is incorrect.
TIBA (2,3,5-triiodobenzoic acid) is an auxin transport inhibitor, not a gibberellin inhibitor — Statement (4) is incorrect.
Information Booster:
Auxins regulate cell elongation differentially in roots and shoots.
Ethylene causes triple response: swelling of stem, horizontal growth, slowed elongation.
Cytokinins promote cell division; kinetin was artificially discovered.
TIBA blocks auxin transport pathways.
Gibberellins promote stem elongation and seed germination.
Additional Information (Incorrect Statements):
(2) Wrong bioassay attribution.
(4) Wrong hormone inhibition assignment.