Match the columns and choose the correct combination :
`{:("Column I","Column II"),("(a) Auxin","(i) Colouring test in lemon"),("(b) Gibberellin","(ii) Cell division test in plants"),("(c) Cytokinin","(iii) Avena curvature test"),("(d) Ethylene","(iv) Dwarf corn test"):}`

Options

A. a - iii, b - iv, c - ii, d - i
B. a - I, b - iv, c - ii, d - iii
C. a - iv, b - iii, c - I, d - ii
D. a - ii, b - I, c - iv, d - iii

Answer

To solve the question of matching the columns for plant growth regulators and their respective bioassays, we will analyze each hormone in Column I and identify its corresponding test in Column II.

### Step-by-Step Solution:

1. **Identify Auxin**:
- Auxin is a plant growth regulator responsible for various growth processes, including cell elongation and apical dominance.
- The specific bioassay for auxin is the **Avena curvature test**. This test measures the curvature of a decapitated coleoptile in response to auxin.
- **Match**: (a) Auxin → (iii) Avena curvature test.

2. **Identify Gibberellin**:
- Gibberellin is known for promoting stem elongation and growth.
- The bioassay used to measure gibberellin activity is the **Dwarf corn test**, which assesses the elongation of internodes in corn plants.
- **Match**: (b) Gibberellin → (iv) Dwarf corn test.

3. **Identify Cytokinin**:
- Cytokinins are involved in promoting cell division and growth.
- The appropriate bioassay for cytokinin is the **Cell division test in plants**.
- **Match**: (c) Cytokinin → (ii) Cell division test in plants.

4. **Identify Ethylene**:
- Ethylene is a gaseous hormone that plays a significant role in fruit ripening and other processes.
- The bioassay for ethylene is the **Colouring test in lemon**, which detects the presence of ethylene by observing the color change in lemons.
- **Match**: (d) Ethylene → (i) Colouring test in lemon.

### Final Matching:
- (a) Auxin → (iii) Avena curvature test
- (b) Gibberellin → (iv) Dwarf corn test
- (c) Cytokinin → (ii) Cell division test in plants
- (d) Ethylene → (i) Colouring test in lemon

### Correct Combination:
- The correct combination is:
- (a) → (iii)
- (b) → (iv)
- (c) → (ii)
- (d) → (i)