In order to make students aware of some specific linguistic and grammar aspects, and increase lexical knowledge, a teacher presented them two groups of words to be examined and discussed.

Group 1: coal – festival – meal – litoral – petal – seal – vial – goal
Group 2: arrival – denial – refusal – burial – betrayal – approval – survival – referral

The teacher’s word choice had a didactic intention as he/she planned to ask questions aiming at guiding students’ observations and insights. Choose the item displaying the criterion that justifiesthe teacher’s word choice in both groups.