Answer:
The correct option is (c)
Step-by-step explanation:
Return on investment measures the attractiveness with respect to an investment. It evaluates the efficiency of a particular investment as compared to other investment opportunities.
It is computed by subtracting cost of investment from current value and divide the result by the cost.
In this case, buyer should estimate the return on investment in purchasing larger quantity to get discount and compare it with other investment opportunities. If it offers higher returns, then the buyer should go for this.