(a) Define and explain the four key dimensions of Credit risk, as used to calculate RWA for regulatory capital purposes under the Basel 2/Basel 3 rules (FIRB and AIRB approaches) (13 marks) (b) Describe and explain the various fundamental (as opposed to market based) approaches to modelling PD for Credit Risk purposes, highlighting the limitations of certain approaches for portfolios with low default experience. (12 marks) (c) Define Expected Loss and explain why it is such an important concept in credit management. (8 marks)