Arrange the following cells in an ascending order based on their size.
i) Mycoplasma ii) Ostrich egg
iii) Human RBC iv) Bacterium

Options

A. i, iv, iii, ii
B. i, ii, iii, iv
C. ii, i, iii, v
D. ii, ii, i, v

Answer

To arrange the given cells in ascending order based on their size, we will first identify the approximate size of each cell type:

1. **Mycoplasma**: Mycoplasma are the smallest known cells, with sizes ranging from approximately 0.1 to 0.5 micrometers (µm).

2. **Bacterium**: Bacterial cells typically measure between 3 to 5 micrometers (µm) in length.

3. **Human RBC (Red Blood Cell)**: Human red blood cells have a diameter of approximately 6 to 8 micrometers (µm).

4. **Ostrich Egg**: The ostrich egg is the largest cell, measuring about 15 centimeters (cm) or 150,000 micrometers (µm) in diameter.

Now, let's arrange these cells in ascending order based on their size:

- **Step 1**: Start with the smallest cell, which is **Mycoplasma** (0.1 - 0.5 µm).
- **Step 2**: Next, we have **Bacterium** (3 - 5 µm).
- **Step 3**: Following that is **Human RBC** (6 - 8 µm).
- **Step 4**: Finally, the largest cell is the **Ostrich Egg** (150,000 µm).

Thus, the ascending order based on size is:
1. Mycoplasma
2. Bacterium
3. Human RBC
4. Ostrich Egg

In numerical order, this corresponds to:
1 (Mycoplasma), 4 (Bacterium), 3 (Human RBC), 2 (Ostrich Egg).

### Final Answer:
The correct ascending order is: **1, 4, 3, 2**.