If you are going to write a short story, you don't need to ; you can take some things from real life:

d) all choices are correct

the nets, boats and fishing poles are examples of determinants for catching fish. if a fisherman has a quality fishing net and fishing poles plus a high end fishing boat, then there is a big opportunity or possibility that he may catch more fish.

moreover, fish production is directly proportional to its determinants such as boat, net, fishing poles and bait. therefore, a good equipment is a determinant while fisherman’s effort is an input to his fishing skills and the output is the production made out of catching fish.