For a reaction X Y , the graph of the product concentration (x)...

If product concentration is $x$. For a zero order reaction $\frac{x}{t}=k$ Thus graph would be a straight line passing through origin. So the given information is for zero order reaction. For a zero order reaction, rate of the reaction is constant. Thus, plot of rate $v s$ time, i.e., $-\frac{d[X]}{d t} v s$ time will be a straight line parallel to $x$-axis.