The relationship between the variable input and output, keeping all other inputs constant, is often referred to as _______ of the variable input.

Total Product

The correct answer is Option 1: Total Product 

Total Product: Suppose we vary a single input and keep all other inputs constant. Then for different levels of that input, we get different levels of output. This relationship between the variable input and output, keeping all other inputs constant, is often referred to as Total Product (TP) of the variable input.

Average product is defined as the output per unit of variable input. We calculate it as AP= TP (L)/L

where TP (L) = Total product of variable Factor (Labour)

L is Labour

Marginal product of an input is defined as the change in output per unit of change in the input when all other inputs are held constant. When capital is held constant, the marginal product of labour is =Change in Output/Change in Input

Diminishing Marginal Product: This refers to a specific stage where adding more of the variable input results in a declining marginal product, but it does not define the overall relationship between input and output.