5. C
(1) If $S A=S B=S C=B C=1$.
$S A \perp S B, S A \perp S C$. Then $V_{S A L E}=V_{A-S D C}=\frac{\sqrt{3}}{12}$;
(2) If $S B=S C=B C=1, S A=\frac{\sqrt{2}}{2}$.
$S A \perp A B, S A \perp A C$, then $V_{S-A B}:=\frac{\sqrt{2}}{24}$;
(3) If $S A=S B=A B=A C=B C=1, S C=\sqrt{2}$,
$S A \perp A C, S B \perp B C$, then $V_{S-A B C}=V_{A-S C C}=\frac{\sqrt{2}}{12}$.
5. A three-dimensional triangular pyramid has two of its three sides as isosceles right triangles, and the other is an equilateral triangle with a side length of 1. The volume of this triangular pyramid is ( ).
A. A uniquely determined value
B. Two different values
C. Three different values
D. More than three different values