It has five wheels, though often think four, You cannot use it without that one more, You can put things in it, you can strap things on top, You can’t find it in the market, but you can still go shop. What is it?
Someone has stolen Beethoven's Wig and has put it in one of four locked boxes. The boxes are numbered from 1,2,3,4 in that order. There are four different keys that each has their own color. Use the clues below to figure out which key goes in which box and to find the box where Beethoven's wig is being kept.