The diameter of a human red blood cell is(a) 15 μm(b) 8.2 μm(c) 2 μm(d) 50 μm

To solve the question about the diameter of a human red blood cell, we need to understand the general size range of red blood cells.

Human red blood cells (erythrocytes) typically have a diameter of about 6 to 8 micrometers (μm).

Now, let's examine the options provided:

(a) 15 μm - This is larger than the typical size of a red blood cell.
(b) 8.2 μm - This is within the typical size range.
(c) 2 μm - This is much smaller than the typical size of a red blood cell.
(d) 50 μm - This is significantly larger than the size of a red blood cell.

Given this analysis, the correct answer is:

(b) 8.2 μm

This value is the most accurate representation of the diameter of a human red blood cell.