We know that the equation of x-axis is y = 0 and the equation of any line parallel to x-axis is y = k, therefore, the reason is true.

For, y = mx

If we put x = 0 then, y = m×0 = 0 therefore, we get (0, 0) which is origin. So, y = mx represents a line passing through the origin, therefore, the assertion is true.

The blue line is the graph of y = mx which clearly, passes through origin.

Hence, both Assertion (A) and Reason (R) are true but Reason (R) is not a correct explanation of Assertion (A).