Concept:The expression inside the square root can be rewritten as a perfect square using the identity (a+1)2=a2+2a+1.Explanation:First, rewrite 12346 as 12345+1.Then the expression becomes (12345)2+12345+(12345+1).Combine terms: (12345)2+2×12345+1.This matches the form a2+2a+1 with a=12345, so it equals (12345+1)2=(12346)2.Finally, (12346)2=12346.Answer:12346 (Option B)