Fullerton companys master budget calls for production and sale of 1,000 units for $5,000; variable costs of $2,000; and fixed costs of $1,000. During the most recent period, the company incurred $2,200 of variable costs and $1,100 of fixed costs to produce and sell 1200 units for $5,100. What is the sales volume variance for operating income?

$900 unfavorable

$500 favorable

$800 favorable

$400 unfavorable