CMBS issuance is $1,550,000,000, of which AAA tranches total $1,356,250,000 of the principal balance. The AA tranche is $62,000,000 and the Single A trench is $55,800,000. the subordination level, expressed a percent, of the Single A tranche is?

a) 11%

b) 4.9%

c) 85.%

d) 3.9%