Consider a Garch(1,1) process, (σt)²=ω+α(rt-1)²+β(σt-1)² , if α+β<1​​​​​​​ and the current volatility is smaller than the long run volatility, the volatility term structure estimated from this Garch(1,1) has:
a A downward-sloping curve and then becomes a straight line
b An upward-sloping curve
c A flat Curve
d A downward-sloping curve