If the yield curve is upward sloping, which of the following statements is correct?

Select one:

a. The default risk premium on T-bonds decreases as years to maturity (T) increases.

b. The maturity risk premium on T-bonds decreases as years to maturity (T) increases.

c. The inflation premium on T-bonds has to increase with maturity (T).

d. The liquidity risk premium on T-bonds decreases as years to maturity (T) increases.

e. The real risk-free rate on T-bonds remains the same as years to maturity (T) increases.