We have been given that the profit that the vendor makes per day by selling x pretzels is given by the function
. We are asked to find the number of pretzels that must be sold to maximize profit.
First of all, we will find the derivative of our given function.


Now, we will find the critical point by equating derivative with 0 as:





Therefore, the company must sell 300 pretzels to maximize profit and option B is the correct choice.