Blood banks are highly dependent on donors. In the terminology of industry analysis, which of the following statements about donors is accurate?

Select one

A$.$ Blood donors are suppliers and are powerful because of the critical nature of what they provide to the blood bank.

B$.$ Blood donors are suppliers and are powerful because of their concentration relative to the blood bank.

C$.$ Blood donors are buyers and are not powerful because switching costs to change to alternative inputs are low.

D$.$ Blood donors are buyers and are powerful because of the volume of blood needed.