Answer:
b) Expectations of higher short-term interest rates in the future
Explanation:
When the yield curve is normal (upward sloping) it is because investors expect longer-maturity bonds to have a higher yield than shorter-maturity bonds, since interest rates are expected to rise in the long term.
On the contrary, if the yield curve is flat, it is because short-maturity and long-maturity bonds are giving the same, or almost the same yield, indicating that investors expect short-term interest rates to rise so much, that they compensate the capital gains for short-maturity bonds in terms of interst.
