Step 1: Recall formula.
Profit = Total Revenue – Total Cost.
Step 2: Evaluate each option.
- (A) Cost of production = expenses incurred to produce goods, not difference.
- (B) Input cost = cost of resources, not difference.
- (C) Marginal cost = change in total cost due to one more unit, not relevant here.
- (D) Profit = correct, the residual after subtracting costs from revenue.
Step 3: Conclusion.
The difference between revenue and cost is called profit.
Final Answer:
\[
\boxed{\text{Profit}}
\]