Define an operation "*": for natural number n, it satisfies the following operation properties: (I) 1 * 1 = 1, (II) (n + 1) * 1 = n * 1 + 1, then n * 1 equals () A. nB. n+1C. n-1D. n2

Define an operation "*": for natural number n, it satisfies the following operation properties: (I) 1 * 1 = 1, (II) (n + 1) * 1 = n * 1 + 1, then n * 1 equals () A. nB. n+1C. n-1D. n2

∵1*1=1,(n+1)*1=n*1+1,∴(n+1)*1=n*1+1=(n-1)*1+1+1=(n-2)*1+3=… =[n - (n-1)] * 1 + n = 1 + N, n * 1 = n