Don't be afraid to go for the obvious choices! If you chose ones which are too loosely linked it doesn't look like you have a strong understanding of the topic. Talk about the problems of grouping and discuss/argue why this doesn't fit in here/there can't fit neatly together. Go past the surface level, make sure you're explaining rather than merely describing what you're linking and try to use the right terminology. Try to get at least 3 groupings but your groupings can be of only two texts (however, if you do this try to cover all the texts and use detailed analysis).