Answer:
The function f(x) * p(x) represents the revenue from selling f(x) frozen yogurts at the price p(x) per yogurt. (First option)
Explanation:
Recall that the revenue is defined as the product of the price per object sold times the number of sales. In our case, the price per object (frozen yogurt) is given by p(x), and f(x) represents the number of customers that are expected to purchase frozen yogurt according to the number of "x" $0.75 increases over $4. This is clearly a problem of "increase-decrease" where as the variable x increases (number of $0.75 increases), one of the functions decreases (in this case the number of possible sales), while the other function increases (in this case the actual price per yogurt).
Therefore, the product of the two functions represents the total revenue from selling f(x) frozen yogurts at a price p(x) per yogurt. This coincides with the first option given among the listed answers.