Hermaphrodites are animals that

Options

A. possess both male and female reproductive system
B. have the gonads of one sex bu the external appearance of the other
C. develop from unfertilized eggs
D. must fertilize themselves

Answer

### Step-by-Step Text Solution:

1. **Understanding Hermaphroditism**: Hermaphrodites are organisms that possess both male and female reproductive systems. This means that a single individual has the capability to produce both sperm and eggs.

2. **Examples of Hermaphrodites**: A common example of a hermaphrodite is the earthworm. In earthworms, there are no distinct male or female individuals; instead, each worm has both reproductive organs.

3. **Analyzing the Options**:
- **Option A**: "Possess both male and female reproductive system" - This is the correct definition of hermaphrodites.
- **Option B**: "Have the gonads of one side but the external opinions of the other" - This is incorrect as it suggests a separation of reproductive organs which does not define hermaphroditism.
- **Option C**: "Develop from unfertilized eggs" - This refers to parthenogenesis, not hermaphroditism.
- **Option D**: "Must fertilize themselves" - While some hermaphrodites can self-fertilize, this is not a defining characteristic of all hermaphrodites.

4. **Conclusion**: Based on the definitions and examples provided, the correct answer to the question "Hermaphrodites are animals that" is **Option A: possess both male and female reproductive system**.