How many distinct words can be formed using all letters of BIHAR?

Correct answer: 120

This is a permutation of all the letters because different orders produce different words. BIHAR contains five letters: B, I, H, A, and R. Each letter occurs only once, so there is no repetition to divide out. The first position can be filled in 5 ways, the second in 4 ways, and so on, giving 5 × 4 × 3 × 2 × 1 = 5! = 120. Therefore, option B is correct. The value 60 is only half of the required factorial count, 25 does not represent arranging five distinct letters, and 10 is also not obtained from the permutation rule. Since every letter must be used exactly once, the appropriate formula is n!, not a combination formula.