In regards to deciding whether a product line or business segment should be added or dropped, which of the following is correct?

a) A product or segment whose revenue do not cover its variable and traceable fixed costs should usually be dropped.

b) Fixed costs are irrelevant in decisions about whether a product or segment should be dropped.

c) A product or segment should be charged for rent in proportion to the space it occupies even if the space has no alternative use and the rental payment is unavoidable in deciding whether to drop the product or segment.

d) The variable costs of a product or segment are not necessarily relevant in a decision considering whether to eliminate it.