How many coordinate axes, mutually at right angles to each other, are set up in the Cartesian coordinate system?

The correct answer is option 3):(Three)

Concept:

• A Cartesian coordinate system in a plane is a coordinate system that specifies each point uniquely by a pair of numerical coordinates, which are the signed distances to the point from two fixed perpendicular oriented lines, measured in the same unit of length.
• In three-dimensional space, the Cartesian coordinate system is based on three mutually perpendicular coordinate axes: the x-axis, the y-axis, and the z-axis illustrated below. The three axes intersect at the point called the origin
• Each reference coordinate line is called a coordinate axis or just axis of the system, and the point where they meet is its origin,  (0,0, 0). The coordinates can also be defined as the positions of the perpendicular projections of the point onto the three axes, expressed as signed distances from the origin.