A manufacturer of tiling grout has supplied the following data:

Kilograms produced and sold 330,000
Sales revenue $1,920,000
Variable manufacturing expense $957,000
Fixed manufacturing expense $260,000
Variable selling and administrative expense $360,000
Fixed selling and administrative expense $226,000
Net operating income $117,000
The company's contribution margin ratio is closest to:

a. 50.2%
b. 81.3%
c. 31.4%
d. 74.7%