Liquidity preference theory

Sir

There is a MTQ question in cbe sample dec 2016 that which of the following statements is consistent with an upward-sloping yield curve?

Correct ans was :
Liquidity preference theory implies that short-term interest rates contain a premium over long-term interest rates to compensate for lost liquidity

But how this can be correct , what we have studied in liquidty preference theory is that the required return increases with the length of time for which the cash is unavailable, therefore, long-term interest rates are greater than short-term interest rates and the yield curve slopes upward