Considering size, which of the following series is the most appropriate ?

Options

A. bacteria `gt` viruses `gt` yeast
B. hornwords `gt` mosses `gt` liverworts
C. smooth muscle cell `lt` striated muscle cell `lt` cardiac muscle cell
D. platelets `lt` human erythrocytes `lt` human eosinophils

Answer

To determine which series is the most appropriate when considering the size of blood components, we can analyze the sizes of platelets, red blood cells (RBCs), and eosinophils.

### Step-by-Step Solution:

1. **Identify the Sizes of Blood Components:**
- Platelets: Approximately 2 to 3 micrometers in diameter.
- Red Blood Cells (RBCs): Approximately 6 to 7 micrometers in diameter.
- Eosinophils: Approximately 12 micrometers in diameter.

2. **Compare the Sizes:**
- Platelets are the smallest, ranging from 2 to 3 micrometers.
- RBCs are larger than platelets, measuring about 6 to 7 micrometers.
- Eosinophils are the largest among the three, with a size of about 12 micrometers.

3. **Establish the Order of Size:**
- From smallest to largest, the order is:
- Platelets (2-3 micrometers)
- Red Blood Cells (6-7 micrometers)
- Eosinophils (12 micrometers)

4. **Select the Correct Option:**
- Based on the sizes, the most appropriate series in terms of size from smallest to largest is: Platelets < RBCs < Eosinophils.
- Therefore, the correct option is the fourth one, which indicates that eosinophils are the largest.

### Final Answer:
The most appropriate series considering size is: Platelets < RBCs < Eosinophils. Thus, the correct option is the fourth option.