Eggs and bunnies

Easter is coming and it's time to start enjoying all those chocolate treats. In my household we have four beautifully wrapped boxes, which I bought at the same time from the same shop, but unfortunately I have forgotten exactly what is inside.

What I can remember is this: There are four boxes and each contains either a chocolate bunny, or a chocolate egg, and the chocolate is either white, or dark. I lay out the boxes in a row and after thinking for a moment I remember a little bit about what I bought.

The first box definitely contains an egg, the second definitely contains a bunny, the third is definitely made of white chocolate and the last one is definitely made of dark chocolate.

Being a budding chocolate lover, my son, James, wants me to confirm that all the bunnies I bought are made of dark chocolate. Now, I'm fairly sure that all the bunnies I bought were made of dark chocolate and I know that I can confirm this by opening only two of the boxes, but which boxes do I need to open?

If you are stumped by last issue's puzzle, here is the solution.

For some challenging mathematical puzzles, see the NRICH puzzles from this month or last month.