Birthday Invite Question!

ktshoff

My DS is having a bowling party next month.  He goes to am preschool and there are 20 kids in his class.  Then he goes to a daycare for after care.  That place is huge and he talks about 4 kids that he plays with all the time.

Now, how in the world do I decide who to invite.  Should I invite his whole pre K class and just hand out the 4 invites at his daycare?  Is that rude?? WWYD?!?!?

Thanks!