Answer:
D. 33%.
Explanation:
The gross margin (markup rate) can be calculated as follows:
Gross margin = (selling price - cost price) / selling price
In this case, the cost price of the skillet is $20 and the selling price is $30, so:
Gross margin = ($30 - $20) / $30
= $10 / $30
= 0.33 or 33%
Therefore, the answer is D. 33%.