Abscissa of a point on the x-axis
The abscissa of a point on the x-axis refers to the x-coordinate of that point. In other words, it is the distance of the point from the y-axis.

Understanding the x-axis
The x-axis is one of the two perpendicular number lines in a Cartesian coordinate system. It is the horizontal line that intersects the y-axis at the origin point (0,0). The x-axis extends infinitely to the right and left.

Abscissa options
a) 1
b) 0
c) x
d) 1

Explanation of the correct answer
The correct answer is option 'c' - x. This is because the abscissa of any point on the x-axis is represented by the variable x. The x-coordinate of any point on the x-axis is equal to its distance from the y-axis, which is always 0.

Explanation of the incorrect options
a) 1: This option is incorrect because the abscissa of a point on the x-axis is not always 1. It can be any real number, not just 1.
b) 0: This option is incorrect because the abscissa of a point on the x-axis is not always 0. The abscissa represents the x-coordinate, which can vary depending on the position of the point on the x-axis.
d) 1: This option is incorrect for the same reason as option 'a'. The abscissa is not always 1; it can be any real number.

Conclusion
The abscissa of any point on the x-axis is represented by the variable x. It can be any real number, indicating the distance of the point from the y-axis.