In a fertilised embryo sac, the haploid, diploid and triploid structures are

Options

A. synergid, zygote and primary endosperm nucleus
B. synergid, antipodal and polar nuclei
C. antipodal, synergid and primary endosperm nucleus
D. synergid, polar nuclei and zygote

Explanation

To answer the question about the haploid, diploid, and triploid structures in a fertilized embryo sac, we can break down the information as follows:

### Step-by-Step Solution

1. **Identify the Structures in the Embryo Sac**:
- The embryo sac contains several cell types, including synergids, antipodals, polar nuclei, and the zygote.

2. **Determine the Ploidy Levels**:
- **Haploid (n)**: This refers to cells that have one set of chromosomes. In the embryo sac, the following structures are haploid:
- **Synergids**: These are the two cells located at the micropylar end of the embryo sac.
- **Antipodal Cells**: These are the three cells located at the chalazal end of the embryo sac.
- **Diploid (2n)**: This refers to cells that have two sets of chromosomes. In the embryo sac:
- **Zygote**: This is formed after fertilization when the male gamete (n) fuses with the female gamete (n), resulting in a diploid zygote (2n).
- **Triploid (3n)**: This refers to cells that have three sets of chromosomes. In the embryo sac:
- **Primary Endosperm Nucleus**: This is formed by the fusion of one male gamete (n) with the central cell (which contains two polar nuclei, making it 2n), resulting in a triploid structure (3n).

3. **Summarize the Findings**:
- **Haploid Structures**: Synergids (n) and Antipodals (n).
- **Diploid Structure**: Zygote (2n).
- **Triploid Structure**: Primary Endosperm Nucleus (3n).

4. **Match the Structures with the Given Options**:
- The correct answer includes the haploid, diploid, and triploid structures identified above.

### Final Answer
In a fertilized embryo sac:
- **Haploid Structures**: Synergids and Antipodals (n)
- **Diploid Structure**: Zygote (2n)
- **Triploid Structure**: Primary Endosperm Nucleus (3n)

Thus, the correct answer is: **Synergids (n), Zygote (2n), and Primary Endosperm Nucleus (3n)**.