Answer:
The answer is a): 38%. 
Step-by-step explanation:
Contribution margin ratio is a ratio of the difference between sales and variable costs/expenses, to the sales; it can be expressed in percentage. 
Sales = $425,000
Variable costs = 62% of $425,000 = 62 × $425,000 ÷ 100 = $263,500
. 
The difference between sales and variable cost = $425,000 — $263,500 = $161,500
. 
Therefore, the contribution margin ratio = $161,500 ÷ $425,000 = 0.38 
The contribution margin ratio expressed in percentage = 0.38 × 100 = 38%
.