Answer:
The correct option is B.
Step-by-step explanation:
The marginal benefit is the maximum amount which a person or individual is willing to pay in order to have an additional service or benefit. It is the additional satisfaction, which the person receives when an additional service or good is purchased.
So, in this case, Cassie need or require some special fabric which cost her $200 that is the additional amount she need to pay in order to complete the task. But alternatively, she could sell the quilt for $900. Therefore, she had a marginal benefit of $900, if sells the quilt as is now.