The true statement regarding the key features of a linear graph is:
The points will make a straight line.
Linear graphs represent a constant rate of change, resulting in a straight line when plotted on a Cartesian coordinate system. The other statements are not necessarily true: the initial value (y-intercept) can be any value (not just zero), the points can have negative values, and the rate of change (slope) is constant along a linear graph, not varying.