Ans: C
All possibilities are
All possibilities are
$\begin{array}{llcl}
1. & 1 + 2 + 5 & = & \$ 8 \\
2. & 1 + 2 + 10 & = & \$ 13 \\
3. & 1 + 5 + 10 & = & \$ 16 \\
4. & 2 + 5 + 10 & = & \$ 17
\end{array}$
Therefore, the required probability is $\dfrac{3}{4}$.
