Which one is false?

Options

A. Both cartilaginous and bony fishes are dioecious
B. Cartilaginous fishes show sexual dimorphism
C. Male cartilaginous fish has claspers
D. Female cartilaginous fish has claspers

Answer

To determine which statement is false regarding cartilaginous fishes, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding the Options**:
- **Option 1**: Both cartilaginous and bony fishes are dioecious.
- **Option 2**: Cartilaginous fishes show sexual dimorphism.
- **Option 3**: Male cartilaginous fish has claspers.
- **Option 4**: Female cartilaginous fish has claspers.

2. **Analyzing Option 1**:
- The term "dioecious" means that the species have distinct male and female individuals. Both cartilaginous fishes (like sharks and rays) and bony fishes are indeed dioecious. Therefore, this statement is **true**.

3. **Analyzing Option 2**:
- Sexual dimorphism refers to the differences in appearance between males and females of the same species. Cartilaginous fishes do exhibit sexual dimorphism, allowing for differentiation between males and females. Thus, this statement is **true**.

4. **Analyzing Option 3**:
- Male cartilaginous fishes possess claspers, which are modified pelvic fins used for reproduction. This is a characteristic feature of male cartilaginous fishes. Therefore, this statement is **true**.

5. **Analyzing Option 4**:
- Female cartilaginous fishes do not have claspers; they are exclusively found in males. This statement is **false**.

### Conclusion:
The false statement is **Option 4: Female cartilaginous fish has claspers**.