Select the correct Statement .
a. Intine of pollen grains is composed of pectocellulosic in nature .
b. Pollen grains develop from the haploid microspore mother cells in pollen sacs of anther.
c. Pollen grain is diploid , unicellular , multinucleate and oval shaped structure.
d. Pollen grains are generally spherical measuring about 20-25 mm in diameter .

Options

A. Only b is correct
B. a ,b,c are correct
C. Only a is correct
D. Only d is correct

Answer

To solve the question, we need to evaluate each of the four statements regarding pollen grains and identify which one is correct.

### Step-by-Step Solution:

1. **Evaluate Statement A:**
- **Statement:** "Intine of pollen grains is composed of pectocellulosic in nature."
- **Analysis:** The intine is indeed composed of cellulose and pectin, which can be referred to as pectocellulosic. This statement is **correct**.

2. **Evaluate Statement B:**
- **Statement:** "Pollen grains develop from the haploid microspore mother cells in pollen sacs of anther."
- **Analysis:** The microspore mother cell is diploid, not haploid. It undergoes meiosis to produce haploid microspores. Therefore, this statement is **incorrect**.

3. **Evaluate Statement C:**
- **Statement:** "Pollen grain is diploid, unicellular, multinucleate and oval shaped structure."
- **Analysis:** Pollen grains are haploid, not diploid, and they are multinucleate (typically containing three nuclei). They are not unicellular as they develop from microspores. Hence, this statement is **incorrect**.

4. **Evaluate Statement D:**
- **Statement:** "Pollen grains are generally spherical measuring about 20-25 mm in diameter."
- **Analysis:** Pollen grains are generally spherical or oval but their diameter ranges from about 25-50 micrometers (not millimeters). Therefore, this statement is **incorrect**.

### Conclusion:
After evaluating all four statements, the only correct statement is **Statement A**.

### Final Answer:
The correct statement is: **A. Intine of pollen grains is composed of pectocellulosic in nature.**

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