Answer: The correct option is (B)

Step-by-step explanation: Given that Alice had
pounds of walnuts at the beginning of the week. At the end of the week, she had
pounds.
We are to find the quantity of walnuts that she had used.
We have
The quantity of walnuts that Alice has is

and the quantity of walnut that she had at the end of the week is

Therefore, the quantity of walnut that she has used is given by

Thus, the required quantity of walnut that she has used is

Option (B) is CORRECT.