3. If the equation $a^{x}-x-a=0$ has two real solutions, then the range of values for $a$ is
A. $(1,+\infty)$
B. $(0,1)$
C. $(0,2)$
D. $(0,+\infty)$
Consider the number of intersection points between the graph of $y=a^{x}$ and the line $y=x+a$. When $a>1$, there are 2 intersection points.  
Therefore, the correct choice is $A$.