1 For the following questions, select the key term that best matches with the definition provided. - A line connecting the least cost combination points along the production surface; also, a line connecting the most profitable combination points for each of a number of production possibilities curves - The relationship between two factors or inputs used in production - The functional relationship between a factor of production and its product - Resources whose marginal rate of substitution changes as their proportions are changed,ceteris paribus. A. Imperfect substitutes B. Expansion path C. Factor-product relationship D. Factor-factor relationship