I need help with part c

Grifols, S.A., is a Spanish pharmaceutical company focusing on the development, manufacturing, and sale of therapeutic products. At the end of 2013, Grifols was rated "BB" by Standard & Poor's and considered to have a stable business risk profile December 31 Grifols, S.A. (euro in thousands) 2013 2012 Operating income after tax 342,054 255,377 Operating profit before interest income, interest expense, & taxes 736,120 660,084 Depreciation and amortization 128,469 129,126 Deferred income tax expense 14,992 97,018 Asset impairment losses (gain) 271 (1,442) Major noncash charges (gain) 14,873 (1, 774) Short term debt 248,706 189,335 Long-term debt 2,437,976 2,585,988 Equity 2, 107,204 1,880,741Required a. What is a credit rating and why would a potential investor in bonds be interested in a company's credit rating? b. What type of factors does a credit rating agency consider in rating a company? c. Compute funds from operations over debt and debt to EBITDA for 2012 and 2013 using the selected financial statement information above. d. Research the financial risk rating by Standard and Poor's and use it as benchmark to asses the financial risk profile of the company for both years