The term 'protobionts' is used for describing the

Options

A. first formed bacteria
B. first formed viruses
C. first formed protozoans
D. first formed cells

Explanation

**Step-by-Step Solution:**

1. **Understanding the Term 'Protobionts':**
- The term 'protobionts' is derived from two parts: "proto" meaning first, and "bion" meaning life or cell.

2. **Identifying the Options:**
- The question provides four options:
a) First formed bacteria
b) First formed virus
c) First formed protozoan
d) First formed cell

3. **Analyzing the Options:**
- Option a (first formed bacteria) and option b (first formed virus) refer to specific types of living organisms that are not the earliest forms of life.
- Option c (first formed protozoan) also refers to a specific group of single-celled organisms, which came later in the evolutionary timeline.
- Option d (first formed cell) refers to the earliest forms of life, which aligns with the definition of protobionts.

4. **Conclusion:**
- Based on the definitions and the options provided, the term 'protobionts' is best described as the "first formed cells." Therefore, the correct answer is option d) first formed cell.

**Final Answer:**
The term 'protobionts' is used for describing the first formed cells.

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