Abscissa of all the points on the x-axis can be any number (b).

Explanation:
Abscissa and ordinate are used to represent the position of a point on a graph as we know.

The abscissa, also known as the x-coordinate, is the distance of a point from the y-axis measured parallel to the x-axis. It represents the horizontal position of the point on the graph.

The ordinate, also known as the y-coordinate, is the distance of a point from the x-axis measured parallel to the y-axis. It represents the vertical position of the point on the graph.

All the points on the x-axis are at 0 distance from the x-axis thus their ordinate or y coordinate is 0.

But these points can be at any distance from the y-axis, thus the x coordinate or the abscissa can be any number.