If, by dropping a product line, a company cannot avoid as much in fixed costs as it loses in contribution margin, the company should the product line.

Keep or retain

Explanation:

Product Line is the term which is defined as the group or the class of the products which are related and are also marketed under the single name of brand, which is sold through the same company.

Companies or business who expand as well as increase their offerings or products or the items through adding the existing products lines as the customers are more likely to buy the products from brands with which they are familiar or already know.

So, if the business would not able to avoid the fixed costs which result in lose of contribution margin, then the company should retain or keep the product line, which would help them in generating the revenues.