The correct option is (a) Prandtl number

Easy explanation: Prandtl number is a dimensionless number used to determine heat convection. It is the ratio of the amount of heat dissipated to the amount of heat conducted. Whereas, Froude number is the ratio of inertial force to gravitational force, Weber number is the ratio of inertial force to surface tension and Reynold’s number is the ratio of inertial force to viscous force.