3. Let $b>a$, the graphs of the linear functions $y=b x+a$ and $y$ $=a x+b$ are drawn in the Cartesian coordinate system, then there is a set of values for $a$ and $b$ such that one of the following 4 graphs is correct ( ).


3. (B)

The intersection point $(x, y)$ of two lines is the solution to the system of equations $\left\{\begin{array}{l}y=b x+a, \\ y=a x+b\end{array}\right.$, which is $(1, a+b)$.
(A) The x-coordinate of the intersection point is 1, a number, so (A) is incorrect.
(C) The x-coordinate of the intersection point is $2 \neq 1$, so (C) is incorrect.
(L) The y-coordinate of the intersection point is a number greater than $a$ and less than $b$, not $a+b$. So (L) is incorrect.
Since only one of the four options is correct, the answer is (B).