Entry of pollen tube into ovule through chalaza was first discovered by treub in a xerophyte. The plant is associated with a pair flowers
(i) unisexual flowers
( ii) sessile flowers
(iii) centripetal arrangement of flowers
(iv) bisexual flowers. The correct pair is

Options

A. ii and iii
B. iii and iv
C. ii and iv
D. I and ii

Explanation

To solve the question regarding the entry of the pollen tube into the ovule through the chalaza, we need to analyze the options provided and determine the correct pair of flower characteristics associated with the plant.

### Step-by-Step Solution:

1. **Understanding the Context**: The question states that the entry of the pollen tube into the ovule through the chalaza was first discovered by Treub in a xerophyte. We need to identify the characteristics of flowers associated with this plant.

2. **Analyzing the Options**:
- **(i) Unisexual flowers**: These are flowers that have either male or female reproductive organs, but not both. This could be a possibility since xerophytes often have adaptations that include unisexual flowers.
- **(ii) Sessile flowers**: Sessile flowers are those that do not have a stalk (peduncle) and are directly attached to the stem. This could also be a characteristic of some xerophytes.
- **(iii) Centripetal arrangement of flowers**: This refers to a floral arrangement where the younger flowers are located towards the center and older flowers towards the periphery. This is less common in xerophytes.
- **(iv) Bisexual flowers**: These flowers contain both male and female reproductive organs. While some plants may have bisexual flowers, the context here suggests a focus on unisexual flowers.

3. **Identifying the Correct Pair**:
- Given that the entry of the pollen tube through the chalaza was first observed in a xerophyte, and considering the nature of xerophytes, the most likely pair of characteristics is **(i) Unisexual flowers and (ii) Sessile flowers**.
- The other options either do not align with the characteristics of xerophytes or are less relevant.

4. **Conclusion**: The correct pair of flower characteristics associated with the plant is **(i) Unisexual flowers and (ii) Sessile flowers**.

### Final Answer:
The correct pair is **(i) Unisexual flowers and (ii) Sessile flowers**.