Rubble Enterprises Develops an Annual Overhead Budget at the Start

Rubble Enterprises develops an annual overhead budget at the start of each year (which has remained unchanged for the last 2 years) , and closes any over- or underapplied overhead at year-end. For the firm's single product the following ending inventory levels have been experienced during the last 7 months: Month Units
December 31 300
January 31 300
February 28 200
March 31 400
April 30 300
May 31 400
June 30 500
In how many months would variable costing income be equal to absorption costing income?

A) 0
B) 1
C) 2
D) 3