5. Danny has as many brothers as he has sisters, and Danny's older sister has exactly twice as many brothers as she has sisters. Then the number of Danny's parents' children is ( ).
(A) 3
(B) 4
(C) 5
(D) 6
(E) 7
5. (E) Let Dan have $x$ brothers and $x$ sisters. Then, his sister has $x+1$ brothers and $x-1$ sisters, and from $x+1=$ $2(x-1)$, we get $x=3$.