On the board there are 16 words. They all fit in one of four groups. On the first board select those that fit together with the first word, on the second with the second word and so on.
The explanations for the groups are in the comments. Don't peek!
Inspired by Wyna Liu's Combinations Games made for the New York Times
Group 2: Words that come before 'gap'. (CUMBERLAND, THE, AGE, GENDER PAY)
Group 3: Last names of superheroes' alter egos. (WAYNE, BANNER, STARK, KENT)
Group 4: Places with natural hot springs. (YELLOWSTONE, BATH, SPA, BANFF)