Which one of the plant growth regulators would you use if you are asked to:
(a) Induce rooting in a twig
(b) Quickly ripen a fruit
(c) Delay leaf senescence
(d) Induce growth in axillary buds
(e) ‘Bolt’ a rosette plant
(f) Induce immediate stomatal closure in leaves.

Explanation

To answer the question regarding which plant growth regulators (phytohormones) to use for specific purposes, we can break it down step by step:

### Solution Steps:

1. **Induce rooting in a twig**:
- The appropriate plant growth regulator for inducing rooting in a twig is **Auxin**. Auxins are known to promote root formation and are often used in plant propagation.

2. **Quickly ripen a fruit**:
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