Australian Year 10 Economics Practice Test

Supply is influenced by the costs of production. When input prices rise, producing goods becomes more expensive, so firms are willing to supply less at each price, and the supply curve shifts left. When input prices fall, production becomes cheaper, and supply increases, shifting the curve right. This direct link between input costs and the amount firms are willing to supply makes input prices a determinant of supply.

Consumer income and tastes affect demand, not supply, and advertising mainly influences demand as well. So the statement about input prices affecting production costs and shifting supply correctly identifies a determinant of supply.