Promotion planning -> SD-CO-PA relationship

Can anybody give me brief explanations for the answers of the following multiple choice question (answers for each choice)?

Thanks in advance for the answers...

Which of the following statements are correct regarding promotion planning?

(a) Accurate reporting is possible because data can be transferred from SD to CO-PA at three different stages.

(b) Budgets are created as planning versions in CO-PA for sales and marketing strategies. Agreements, such as sales deals for marketing campaigns are created in SD.

(c) In the agreement, planned values for the condition records can be passed to CO-PA as a commitment.

(d) Budgets can be monitored by comparing the two versions (budget vs. commitment)