Filiform apparatus is a characteristic feature of

Options

A. egg
B. synergid
C. zygote
D. suspensor

Explanation

**Step-by-Step Solution:**

1. **Understanding the Embryo Sac**: The first step is to identify what the embryo sac is. The embryo sac is a structure found in the female reproductive organ of flowering plants, and it contains the egg cells, which are the female gametes.

2. **Identifying the Components of the Embryo Sac**: Within the embryo sac, there are several types of cells, including the egg cell and synergids. The synergids are located at the micropylar end of the embryo sac.

3. **Defining the Filiform Apparatus**: The filiform apparatus is a specific feature associated with the synergids. It consists of finger-like projections that extend from the synergid cells.

4. **Functions of the Filiform Apparatus**: The filiform apparatus has two main functions:
- **Guiding the Pollen Tube**: It helps guide the entry of the pollen tube into the embryo sac. The pollen tube carries the sperm cells necessary for fertilization.
- **Transporting Nutrients**: It assists in the transport of nutrients from the surrounding cells (mucilus cells) to the embryo sac, providing nourishment to the developing embryo.

5. **Conclusion**: Based on the above information, we can conclude that the filiform apparatus is a characteristic feature of the synergids within the embryo sac.

**Final Answer**: The filiform apparatus is a characteristic feature of **synergids**.

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