3 For the following questions, select the key term that best matches with the definition provided. - A resource used to produce a valued product or service - The physical effort of humans that is combined with other resources to produce valued goods and services - All the productive attributes of the earth's surface, including space and the natural environment - As successive amounts of a variable input are combined with a fixed input, the total product will increase, reach a maximum, and eventually decline A. Law of diminishing returns B. Land C. Labor D. Input