A cement manufacturer has supplied the following data:
Tons of cement produced and sold 235,000
Sales revenue $939,000
Variable manufacturing expense $255,000
Fixed manufacturing expense $289,000
Variable selling and administrative expense $120,600
Fixed selling and administrative expense $85,000
Net operating income $189,400
The company's contribution margin ratio is closest to:_________
a) 42.1%
b) 69.2%
c) 60.0%
d) 20.2%