External fertilisation is absent in

Options

A. bony fishes
B. reptiles
C. frogs
D. majority of algae

Answer

**Step-by-Step Solution:**

1. **Understanding External Fertilization:**
- External fertilization occurs when the fusion of male and female gametes happens outside the female body. This is common in many aquatic organisms where eggs and sperm are released into the water.

2. **Analyzing the Options:**
- **Option A: Bony Fishes**
- Bony fishes, such as sharks, typically exhibit external fertilization. The female releases eggs into the water, and the male releases sperm to fertilize them outside the body.
- **Option B: Reptiles**
- Reptiles, including snakes and lizards, have internal fertilization. This means that fertilization occurs inside the female's body, making external fertilization absent in this group.
- **Option C: Frogs**
- Frogs are known for external fertilization. The female lays eggs in water, and the male fertilizes them externally.
- **Option D: Majority of Algae**
- Most algae also reproduce through external fertilization, where gametes are released into the water for fertilization.

3. **Conclusion:**
- Based on the analysis, the group of organisms where external fertilization is absent is **Option B: Reptiles**.

**Final Answer:** External fertilization is absent in reptiles.

---