Which one of the statement is true?

Options

A. All organ system level animals have tube within tube plan
B. All blind sac animals contain bigerminal conditions lion
C. Animals having radial symmetry contain blind sac body plan
D. All chordates are vertebrates but all vertebrates are not chordates

Answer

To determine which statement is true among the given options, we will analyze each statement step by step.

### Step-by-Step Solution:

1. **Analyze the First Statement**:
- The first statement claims that "all organ system level animals have a tube within the tube plan."
- This statement is true. Organ system level animals, which include higher-level organisms, typically possess a body plan characterized by two openings: a mouth and an anus, forming a tube-like structure.

2. **Analyze the Second Statement**:
- The second statement states that "all blind sac animals contain a bi-germinal condition."
- This statement is incorrect. Bi-germinal condition refers to a disease state and is not a characteristic of blind sac animals, which typically have a single opening.

3. **Analyze the Third Statement**:
- The third statement claims that "animals having radial symmetry contain a blind sac body plan."
- This statement is also incorrect. While some animals with radial symmetry may have a blind sac body plan, not all do. There are radial animals that do not exhibit this body plan.

4. **Analyze the Fourth Statement**:
- The fourth statement asserts that "all chordates are vertebrates."
- This statement is false. While all vertebrates are chordates, not all chordates are vertebrates. Chordates include a broader range of organisms, including those that do not have a backbone.

5. **Conclusion**:
- After evaluating all the statements, the only true statement is the first one: "all organ system level animals have a tube within the tube plan."

### Final Answer:
The true statement is: **All organ system level animals have a tube within the tube plan.**