Correct Answer: B
Explanation:
Using Euclid’s division lemma –
n = 9(q) + 7, where q is the quotient when divided by 9.
3n = 9(3q) + 21 { multiply by 3 on both sides }
3n = 9(3q) + 18 + 3
3n = 9(3q + 2) + 3 (I)
Also when (3n - 1) divided by 9 -
3n - 1 = 9(p) + r, where r is the remainder and p is the quotient.
3n = 9p + r + 1 (II)
Comparing I and II –
r + 1 = 3
r = 2.