@SHAKHI There is two things which we have to remember in that setIrfan has to practice all three aspects on a particular day.Three should not be gap of more than two days.
Now coming to your doubt.. among 3rd,4th and 5th day is the day where he practices all three aspects. If he does practices on 4th day then the gap between fielding is 3 days. Same case with 3rd day also. 5th day is the day which is satisfying above cases. Hence 5th day is wednesday.
I hope it's clear now.