What is the recommended solution to address these requirements?

Universal Containers (UC) has a multi-level master-detail relationship for opportunities, a custom opportunity line item object, and a custom discount request. UC has opportunity as master and custom line item object as detail in master-detail relationship. UC also has a custom line item object as master and a custom discount request object as detail in another master-detail relationship. UC has a requirement to show all sums of discounts across line items at an opportunity level.

What is the recommended solution to address these requirements?
A . Use roll-up for the line-item-level summary and a trigger for the opportunity amount summary, as only one level roll-up is allowed.
B. Update the master-detail relationships to lookup relationships in order to allow the discount amount to roll up.
C. Remove the master-detail relationships and rely completely on workflow/triggers to summarize the discount amount.
D. Roll-up discount request amount at the line-item-level and line-item-level summary discount at the opportunity level.

Answer: D