The animals in which cells are organized into structural and functional units called as tissues, organs, and organ system are grouped under which subkingdom ?

Options

A. Parazoa
B. Eumetazoa
C. Metazoa
D. Bilateria

Answer

To determine the subkingdom under which animals with organized cells into tissues, organs, and organ systems are classified, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about animals whose cells are organized into structural and functional units like tissues, organs, and organ systems.

2. **Identifying the Options**: The options provided are:
- A. Parazoa
- B. Eumetazoa
- C. Metazoa
- D. Bilateria

3. **Analyzing Parazoa**: Parazoa refers to simpler organisms, such as sponges, which do not have true tissues or organs. Therefore, they do not fit the criteria of having organized cells into tissues, organs, and organ systems.

4. **Analyzing Eumetazoa**: Eumetazoa includes more complex animals that possess true tissues and organ systems. This group is characterized by a higher level of organization, which aligns with the question's criteria.

5. **Analyzing Metazoa**: Metazoa is a broader category that includes both Parazoa and Eumetazoa. While it encompasses all animals, it does not specifically refer to those with organized structures.

6. **Analyzing Bilateria**: Bilateria refers to animals with bilateral symmetry. While many bilaterally symmetrical animals have organized tissues and organs, this term does not specifically denote the presence of tissues and organ systems.

7. **Conclusion**: Based on the analysis, the correct answer is **B. Eumetazoa**, as it specifically refers to animals that have cells organized into tissues, organs, and organ systems.

### Final Answer:
The animals in which cells are organized into structural and functional units called as tissues, organs, and organ systems are grouped under the subkingdom **Eumetazoa**.

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