Please explain how to get the answer. it should be D but i dont know why

During 2017 the Snell Consulting Company experienced the following three events: The balance in their Unearned Consulting Revenue account decreased $90,000 from January 1 to December 31. No additional Unearned Revenue was booked in 2017. The balance in their Prepaid Rent account decreased $70,000 from January 18 to December 31st. No additional rent was paid in advance in 2017. They declared and paid $5,000 worth of cash dividends (both occurred in 2017) and paid their bank $5,000 cash to repay the principal borrowed with a note payable from 2016. Ignoring interest expense and income tax expense which of the following is Correct for 2017? A. Net Income was $10,000 B. Net Income was $15,000 C. Retained Earnings Increased $20,000 D. Retained Earnings Increased by $15,000 E. Two of the above are correct