Recent research indicates that the spreads on HLT loans behave more like the spreads on investment grade bonds than like the spreads on junk bonds. What of the following is NOT one of the factors that might have played a role?

a$)$ HLT loans are more senior in bankruptcy proceedings

b$)$ HLT loans have greater collateral backing than do high yield or junk bonds.

c$)$ HLT loans have greater stronger covenant protection

d$)$ HLT loans can increase the borrower's financial leverage significantly

e$)$ None of the above.