Please help me 48-50

48. What is the dominant type of structure in the investment-grade credit marke A. the bull B. the floati C. the zero-cou D. the putable structure with an intermediate-term maturity E. the sinking funds structure with a long-term maturity et structure with an intermediate-term maturity ng-rate coupon structure with a long-term maturity coupon structure with a short-term maturity 49. For a mortgage pass-t ugh security, which of the following risks most likely increases as interest rates decline? A. Extension risk B. Balloon risk C. Contraction risk D. Default risk E. Call risk 50. Credit risk is a factor f or commercial mortgage-backed securities because they are backed by mortgage loans that A. have limited call protection B. have no prepayment penalty points C. have prepayment points D. have unlimited call protectiorn E. are non-recourse