Which of the following statements is true?

a.When production is greater than sales, operating income will be equal under variable costing and absorption costing

b.When production is greater than sales, operating income will be lower under absorption costing than variable costing.

c.When production is equal to sales, operating income will be greater under variable costing than absorption costing.

d.When production is less than sales, operating income will be lower under absorption costing than variable costing.