Answer:
The answer is b. Up to $4 million.
Explanation:
It is critical to recognize that $3 million already spent on developing the product is the sunk cost, which is irrelevant cost that should not be included in the budget further spend for the new product.
As the new product is expected to generate a revenues of $4 million, the further cost should be spent on the new product development should not be exceeded the $4 million.
Thus, the answer is b. Up to $4 million is the correct choice.