**Concept: The question tests on the application of the concepts of Counting**

**Solution:**

By the rule of permutations/Arrangements for an n letter word containing x similar letters of 1 type, y similar letters of another type and so on, the number of words that can be formed = n! / (x! * y!...)

TWIST has 5 letters, with 2 T's. therefore the number of words that can be formed = 5! / 2! = 120 / 2 = 60

**Option C**