Through the earthworm is bisexual, but even then always cross-fertilization occurs. Give the reason.

Explanation

### Step-by-Step Solution:

1. **Understanding Bisexuality in Earthworms**:
- Earthworms possess both male and female reproductive organs, which means they are classified as bisexual organisms. This means that each earthworm has the capability to produce both sperm and eggs.

2. **Definition of Cross-Fertilization**:
- Cross-fertilization refers to the process where the sperm from one individual fertilizes the eggs of another individual, rather than self-fertilization where an organism fertilizes its own eggs.

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