Which statement is true about the venous blood vessels of frog?

Options

A. Lingual and submandibular unite to from internal jugular.
B. Musculo-cutaneous and brachial unite to from the subclavian.
C. The ventral abdominal vein drains into the posterior vena cava.
D. The pelvic veins unite to from the renal portal vein.

Answer

To determine which statement is true about the venous blood vessels of frogs, we need to analyze the provided options step by step.

### Step-by-Step Solution:

1. **Evaluate the First Option**:
- The first option states that the lingual and submandibular veins unite to form the interjugular vein.
- This statement is **incorrect** because the lingual and submandibular veins actually unite to form the **external jugular vein**, not the interjugular vein.

2. **Evaluate the Second Option**:
- The second option claims that the musculocutaneous and brachial veins unite to form the subclavian vein.
- This statement is **correct**. The subclavian vein is indeed formed by the union of the brachial vein (which drains the forelimb) and the musculocutaneous vein (which drains blood from the skin and muscles of the body wall).

3. **Evaluate the Third Option**:
- The third option states that the ventral abdominal vein drains into the posterior vena cava.
- This statement is **incorrect** because the ventral abdominal vein actually drains blood into the **hepatic portal vein**, not the posterior vena cava.

4. **Evaluate the Fourth Option**:
- The fourth option claims that the pelvic vein unites to form the renal portal vein.
- This statement is also **incorrect**. The pelvic veins unite to form the **anterior abdominal vein**, not the renal portal vein.

### Conclusion:
After evaluating all the options, the only true statement about the venous blood vessels of frogs is the **second option**, which states that the musculocutaneous and brachial veins unite to form the subclavian vein.

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