Which of these factors ensure fertilization in fishes?

Options

A. Production of small sized gametes
B. Production of gametes in large numbers
C. Production of gametes in remote locations
D. Production of single but very large gamete

Answer

**Step-by-Step Solution:**

1. **Understanding Fertilization in Fishes:**
- Fertilization in fishes primarily occurs through a process known as external fertilization. This means that the male and female gametes (sperm and eggs) fuse outside the bodies of the fish.

2. **Analyzing the Options:**
- **Option A: Production of small-sized gametes**
- This does not directly enhance fertilization since the size of the gametes does not correlate with the likelihood of fertilization.
- **Option B: Production of gametes in large numbers**
- This is crucial for fertilization as it increases the chances of male and female gametes meeting and fusing (syngamy). More gametes mean a higher probability of successful fertilization.
- **Option C: Production of gametes in remote locations**
- While this may affect the environment in which fertilization occurs, it does not inherently ensure fertilization.
- **Option D: Production of single but very large gametes**
- Producing a single large gamete does not increase the chances of fertilization as it limits the number of gametes available for fertilization.

3. **Conclusion:**
- The most effective factor that ensures fertilization in fishes is the **production of gametes in large numbers** (Option B). This increases the chances of syngamy and enhances the survival of the zygote against predators.

**Final Answer:**
- The correct answer is **B. Production of gametes in large numbers.**

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