The standard cost per unit of component X at the ERW company is $4. During November 2020 6,000 units of component X were purchased at a total cost of $25,200. The number of components X used is 7,100 units, but the quantity that should be used for production is 6,900 units. The actual price of component X per unit is.

a. $3,5

b. $4

c. $4,2

d. $3,6