4. From the numbers $1,2,3,4,5$, select several (at least 2) without repetition and find their sum, the number of different sums that can be obtained is ( ) .
(A) 26
(B) 17
(C) 13
(D) 12
4.C.

The sum formed by $1,2,3,4,5$ will not be less than $1+2$ $=3$, and will not be greater than $1+2+3+4+5=15$. Therefore, the number of different sums will not exceed $15-3+1=13$. Furthermore, since these five numbers are consecutive integers starting from 1, each of the 13 different sums can be achieved by substituting $n+1$ for $n$. Thus, there are 13 different sums.