The relationship between the factors of production that a firm uses and the output it produces is called a firm’s production function. A typical production function can be expressed as: Q = TP = f (K, L, N) Here, Q stands for Quantity Output and TP stands for Total Product. When talking about production, these two terms can be used interchangeably. K means physical capital, L means labor and N means land (or natural resources). The correct answer is C.