What Is a Plausible Explanation of a Cost Function Has

Multiple Choice

What is a plausible explanation of a cost function has a slope coefficient of $30 for purchases of 1 to 1,000 units and $25 for production of 1,100 - 2,000 units, and $20 for production of 2,001 - 3,000 units

A) the fixed cost per unit has decreased because of efficiencies
B) economies of scale allowing for lower cost purchases with larger orders
C) their is a linear cost function in effect
D) contribution margins are decreasing