Don't mean to sound rude but you could check with the Form Tr whether 190 is based on your child's usual ability, hard work or luck. If happened to be lucky or have to work super hard, then you should opt for NA as he/she may not cope at Exp. If your child can do better than 190, can consider taking Exp. Howver if the sch environment is very important to you, can always take NA first then try to get into Exp later.
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