Choose the correct statement. (1) Absorbance of blue light by chl. b is more than chl.a (2) Chl a and chl b absorb blue light more than red (3) Absorbance of red light by chl a is more than chl b (4) Carotenoids doesn't absorb red light at all

Options

A. 1 and 3 only
B. 3 and 4 only
C. 2 and 4 only
D. all the above

Answer

To solve the question, we need to evaluate each of the four statements regarding the absorption characteristics of chlorophyll a, chlorophyll b, and carotenoids.

### Step-by-Step Solution:

1. **Evaluate Statement 1**:
- "Absorbance of blue light by chl. b is more than chl.a."
- **Analysis**: Chlorophyll b absorbs blue light more effectively than chlorophyll a. This statement is **correct**.

2. **Evaluate Statement 2**:
- "Chl a and chl b absorb blue light more than red."
- **Analysis**: Chlorophyll a absorbs red light better than blue light, while chlorophyll b also absorbs blue light more than red, but not both absorb blue light more than red. Therefore, this statement is **incorrect**.

3. **Evaluate Statement 3**:
- "Absorbance of red light by chl a is more than chl b."
- **Analysis**: Chlorophyll a is known to absorb red light more effectively than chlorophyll b. This statement is **correct**.

4. **Evaluate Statement 4**:
- "Carotenoids doesn't absorb red light at all."
- **Analysis**: Carotenoids do absorb light, including some wavelengths in the red region, although they are more effective in the blue-green region. Therefore, this statement is **incorrect**.

### Conclusion:
The correct statements are:
- Statement 1: Absorbance of blue light by chlorophyll b is more than chlorophyll a.
- Statement 3: Absorbance of red light by chlorophyll a is more than chlorophyll b.

Thus, the correct answer to the question is **Statement 1 and Statement 3**.