In mammals the urinary bladder opens into

Options

A. Uterus
B. Urethra
C. Vestibule
D. Ureter

Answer

**Step-by-Step Solution:**

1. **Understanding the Urinary System in Mammals**: The urinary system in mammals includes the kidneys, ureters, urinary bladder, and urethra. The primary function of this system is to filter blood and excrete waste in the form of urine.

2. **Identifying the Components**:
- **Kidneys**: These are the organs that filter blood to produce urine.
- **Ureters**: These are the tubes that carry urine from the kidneys to the urinary bladder.
- **Urinary Bladder**: This is the storage organ for urine.
- **Urethra**: This is the tube through which urine exits the body from the urinary bladder.

3. **Focus on the Urinary Bladder**: The urinary bladder is responsible for storing urine until it is ready to be expelled from the body.

4. **Determining the Exit Path**: When urine is expelled from the urinary bladder, it does not exit through the kidneys or ureters. Instead, it exits through the urethra.

5. **Conclusion**: Therefore, in mammals, the urinary bladder opens into the urethra.

**Final Answer**: In mammals, the urinary bladder opens into the urethra.

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