**Concept:** The question tests on the basics of Counting/Combination

**Solution:**

Since all the letters are distinct, another method would be to choose 3 letters out of 6 in 6C3 ways and then arrange them in 3! ways.

6C3 = 6 * 5 * 4 / (3 * 2 * 1) = 20

Total ways = 20 * 6 = 120**Option E**