Analysis of a flow phenomenon in a system requires the following variables:

Pressure [M L-1 T ^-2]

Velocity of the fluid [L T ^-1]

Size of the system [L]

Density of the fluid [M L^-3]

Viscosity of the fluid [M L^-1 T ^-1]

According to Buckingham Pi theorem (dimensional analysis) what is the number of independent DIMENSIONLESS variables needed to describe this system?

(A) 2                           (B) 3                           (C) 4                                 (D) 5