Acme Company produces and sells widgets. Acme's per$-$unit selling price, per$-$unit variabie costs and total fixed costs are constant from year$-$to$-$year. Acme's unit sales are also constant from year$-$to$-$year, but the number of units that Acme produces fluctuates from year$-$to$-$year. Acme's annual operating income computed using variable costing will:

Fluctuate in direct proportion to changes in production.

Fluctuate inversely with changes in production.

Remain constant.

Always be greater than its annual operating income computed using absorption costing.