In which of the following scenarios would it be important to use an outer join to obtain the intended result?

a. Our management team desires a report of all customers who have placed an order.
b. Our management team desires a report of all customers who have placed an order and the total for those orders.
c. Our management team desires a report of all customers and the total of the orders they have placed during the last quarter excluding those customers who placed no order during said quarter.
d. Our management team desires a report of all customers and the total of the orders they have placed during the last quarter including those customers who placed no order during said quarter (their order total would be $0).