Productive resources are the resources used in the production of goods and services. They can also be referred to as factors of production. These factors of production include land, labor, capital, and entrepreneurship. Land refers to natural resources, such as forests and minerals, while labor refers to the human effort required in production. Capital refers to man-made resources, such as machines and tools, while entrepreneurship refers to the ability to combine the other three factors of production to produce goods and services. Therefore, the correct option is "factors of production".