Answer:
D. More Than 1 Solution
Explanation:
Let the system of equations be:


If the graph of equation (1) and (2) are the same, then the two graphs coincide with each other.
What that means is that; the two graphs intersects at infinitely many points.
Therefore the system must have infinitely many solutions.
In other words the system has more than one solution.
NB: At least one solution means exactly one solution and/or more than one solution. But lines that coincide cannot have exactly one solution.