You Are Given a Candle, a Box of Matches, a Few

You are given a candle, a box of matches, a few thumbtacks, and a very short piece of string with the instruction to mount the candle on a wall. It never occurs to you that you could empty the matchbox and tack it to the wall as a platform for the candle because of

A) the framing effect.
B) the sunk cost effect.
C) functional fixedness.
D) an algorithmic dysfunction.