If n=K(K+7), then-
1) k is odd => odd * (odd + Even) = Odd * Odd. We can not say it is multiple of 6 or not. Insufficient.
2) k = 3m +2. So, n=K(K+7) => n= (3m+2)(3m+9)= 3(3m+2)(m+3) => multiple of 3.
If m is odd, m+3 is even. Hence , multiple of 2 and 3. So, it is multiple of 6. Suff.
If m is even, 3m+2 is even. Hence , multiple of 2 and 3 again. So,multiple of 6. Suff.
Ans- B is
1) k is odd => odd * (odd + Even) = Odd * Odd. We can not say it is multiple of 6 or not. Insufficient.
2) k = 3m +2. So, n=K(K+7) => n= (3m+2)(3m+9)= 3(3m+2)(m+3) => multiple of 3.
If m is odd, m+3 is even. Hence , multiple of 2 and 3. So, it is multiple of 6. Suff.
If m is even, 3m+2 is even. Hence , multiple of 2 and 3 again. So,multiple of 6. Suff.
Ans- B is
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