The following set of three words do not at all rhyme with each other :
3. caw / corps / core
1. In the first set gilt / guild / gilet, gilt and guild rhyme with each other.
2. In the second set holy / wholly / holey, all three words rhyme with each other.
4. In the fourth set pare / pair / pear, pair and pare rhyme with each other.
Thus, the correct answer is option 'C'