Sky High sells helicopters. During the current year,

140 helicopters were sold resulting in

$850,000 of sales revenue,

$290,000 of variable costs and

$360,000 of fixed costs.

The number of helicopters that must be sold to achieve $ 310,000

operating income is ________.

A. 168 units

B. 90 units

C. 140 units

D. 111 units