Sexually reproducing multicellular animals start their development from-

Options

A. Gastrula
B. Morula
C. Unicellular zygote
D. Ova

Answer

**Step-by-Step Solution:**

1. **Understanding Sexual Reproduction**: In sexually reproducing multicellular animals, the process begins with the fusion of male and female gametes. The male gamete is typically a sperm, and the female gamete is an ovum (egg).

2. **Formation of Zygote**: When the sperm fertilizes the ovum, they form a diploid cell known as a zygote. This zygote is unicellular, meaning it consists of just one cell.

3. **Development from Zygote**: The zygote undergoes several stages of development. Initially, it divides through a process called cleavage, leading to the formation of a morula (a solid ball of cells) and eventually a blastula and gastrula. However, these stages occur after the zygote stage.

4. **Identifying the Correct Option**: The question asks from which stage the development of multicellular animals starts. The options provided are:
- Gastrula
- Morula
- Unicellular Zygote
- Ova

Among these, the unicellular zygote is the first stage of development after fertilization.

5. **Conclusion**: Therefore, the correct answer is that sexually reproducing multicellular animals start their development from the **unicellular zygote**.

**Final Answer**: C. Unicellular Zygote

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