relevent costing

sorry the question was are general fixed overheads sunk cost , incremental costs or opportunity cost ? it can only be incremental when it is specific fixed overheads which in question i remember didn't mention anywhere about specific . if its sunk cost then why so ?

Fixed overheads are irrelevant unless the total fixed costs change in which case they are committed costs. If they change then the amount of the change is relevant (as an incremental cost). Some people do call the fixed amount sunk costs (because they are payable whatever happens) but that is not really the correct terminology.

if fixed costs are not sunk cost then whats the answer to the question ? there were no other options i remember in the paper ,there were only committed costs sunk costs and incremental. Sunk costs is the right answer ? because general fixed overhead is not incremental cause of the word general. there were no changes mentioned in Question just general fixed overhead and then three options beside it and it asked whats the correct matching.

As I wrote in the first line of my previous reply, they are committed costs.