What colour should my reply card be?

The reply cards are divided into five different colours, corresponding to the five different graduation ceremonies. They are as follows:

Thursday     4 April 2013                18:00               Pink

Friday          5 April 2013                10:00               Green

Friday          5 April 2013                14:30               Blue

Friday          5 April 2013                18:00               Yellow

Saturday      6 April 2013                10:00               Lilac (light purple)