For ideally incompressible fluid, the Mach number will be

The Mach number ($${Ma}$$) is a dimensionless quantity representing the ratio of the speed of an object (or fluid) to the speed of sound in the medium through which it is traveling. It is defined as:

$${Ma} = \frac{v}{c}$$

where:
$${v}$$ is the velocity of the object or fluid.
$${c}$$ is the speed of sound in the medium.

For ideally incompressible fluids, the speed of sound is infinite, and thus the Mach number ($${Ma}$$) is zero. This is because in an incompressible fluid, changes in pressure do not affect the density of the fluid. Therefore, the speed of sound in such a fluid is infinitely high, and any velocity of the fluid will result in a Mach number of zero.

Therefore, the correct answer is Option C: 0.