Final answer:
The simplest form of a graph with no phase shift is a linear graph, representing a rational function.
Step-by-step explanation:
The simplest form of a graph with no phase shift is a linear graph. A linear graph represents a rational function. In a linear graph, the equation for a straight line is y = mx + b, where m is the slope of the line and b is the y-intercept. The slope and y-intercept determine the characteristics of the graph.