If a fisherman must sell all of his daily catch before it spoils for whatever price he is offered, once the fish are caught the fisherman's price elasticity of supply for fresh fish is

Once fish are caught, the quantity is fixed - the fisherman cannot increase or decrease supply regardless of price. This is perfectly inelastic supply (elasticity = 0). Option B (infinite) would mean any quantity can be supplied at one price. Option C (one) is unit elasticity, not perfect inelasticity. The information is sufficient to determine zero elasticity.