In flatworms, fertilisation occurs in the

Options

A. Surrounding water
B. Female genital tract
C. Male genital tract
D. Specialised flame cells

Explanation

### Step-by-Step Solution:

1. **Understanding Flatworms**: Flatworms belong to the phylum Platyhelminthes. They exhibit two modes of reproduction: asexual and sexual.

2. **Asexual Reproduction**: Asexual reproduction in flatworms occurs through processes like fragmentation or budding.

3. **Sexual Reproduction**: In sexual reproduction, there is a fusion of male and female gametes. This is what the question refers to when it mentions fertilization.

4. **Hermaphroditic Nature**: Flatworms are hermaphrodites, meaning that a single organism can produce both male (sperm) and female (egg) gametes.

5. **Modes of Fertilization**: Fertilization can occur in two ways:
- Within the same organism (self-fertilization).
- Between two flatworms (cross-fertilization), where one flatworm's sperm is absorbed by another flatworm.

6. **Location of Fertilization**: The fertilization occurs specifically in the female flatworm's genital tract. This is the correct answer to the question.

7. **Eliminating Incorrect Options**:
- Surrounding water: Incorrect, as fertilization does not occur in water.
- Male genital tract: Incorrect, as fertilization occurs in the female genital tract.
- Specialized flame cells: Incorrect, as flame cells are involved in excretion, not reproduction.

8. **Conclusion**: Therefore, the correct answer to the question "In flatworms, fertilization occurs in the" is **female genital tract**.