2. The sum of all natural numbers $x$ that make the algebraic expression $y=\frac{x^{2}+11}{x+1}$ an integer is ( ).
(A) 5
(B) 6
(C) 12
(D) 22.
2.D.
$y=\frac{x^{2}+11}{x+1}=x-1+\frac{12}{x+1}$. To make $\frac{12}{x+1}$ an integer, the natural number $x$ can take the values $0,1,2,3,5,11$, a total of 6 values, their sum is 22.