Larker Brothers,Inc

Larker Brothers,Inc.,used the high-low method to derive its cost formula for electrical power cost.According to the cost formula,the variable cost per unit of activity is $4 per machine-hour.Total electrical power cost at the high level of activity was $19,200 and at the low level of activity was $18,400.If the high level of activity was 3,300 machine hours,then the low level of activity was:

A) 3,100 machine hours
B) 3,200 machine hours
C) 3,000 machine hours
D) 2,900 machine hours