Single celled animals are said to be immortal because

Options

A. they grow indefinitely in size
B. they can tolerate any degree of change in temperature
C. they can reproduce throughtout their life span
D. they continue to live as their daughter cells.

Explanation

### Step-by-Step Solution

1. **Understanding Immortality**:
- Immortality refers to the ability to live indefinitely without dying. In the context of single-celled organisms, it means that they can continue their lineage without a definitive end.

2. **Reproduction in Single-Celled Animals**:
- Single-celled animals, such as amoeba, primarily reproduce through a process called binary fission. This is a form of asexual reproduction.

3. **Process of Binary Fission**:
- During binary fission, the single parent cell undergoes DNA replication. This means that the genetic material (DNA) inside the parent cell is copied.

4. **Cytokinesis**:
- After the DNA has been replicated, the cell undergoes cytokinesis. Cytokinesis is the process where the cytoplasm of the parent cell divides, resulting in the formation of two new daughter cells.

5. **Formation of Daughter Cells**:
- After cytokinesis, the original parent cell has divided into two daughter cells. Each of these daughter cells contains a copy of the original DNA.

6. **Continued Division**:
- Each daughter cell can continue to divide through binary fission. This means that one parent cell can lead to two daughter cells, which can then each divide to form four, and so on. This process can continue indefinitely.

7. **Lineage Continuation**:
- As the process continues, the genetic material from the original parent cell is passed down through generations of daughter cells. Thus, a part of the original cell continues to exist in its descendants.

8. **Conclusion**:
- Because the genetic material and life cycle continue through successive generations of daughter cells, single-celled animals can be considered "immortal" in the sense that they do not have a definitive end to their lineage.