Open Thermodynamic System:
An open thermodynamic system is one that can exchange both energy and matter with its surroundings. In other words, it allows the transfer of both heat and mass across its boundaries. This type of system is commonly found in many industrial processes and natural phenomena.

Different Options:
Let's analyze each option to determine which one represents an open thermodynamic system:

a) Manual ice cream freezer: This option does not represent an open thermodynamic system. It is a closed system where heat is transferred from the surroundings to the ice cream mixture to freeze it. However, there is no exchange of matter with the surroundings.

b) Centrifugal pump: This option represents an open thermodynamic system. A centrifugal pump operates by continuously drawing in fluid from its surroundings (suction side) and discharging it (discharge side). This process involves the transfer of both energy (work done on the fluid) and matter (fluid flow) across the boundaries of the pump.

c) Pressure cooker: This option does not represent an open thermodynamic system. A pressure cooker is a closed system where the pressure inside increases due to the trapped steam. While there is an exchange of energy (heat transfer) with the surroundings, there is no exchange of matter.

d) Bomb calorimeter: This option does not represent an open thermodynamic system. A bomb calorimeter is a closed system used to measure the heat of combustion of a substance. It does not allow the exchange of matter with the surroundings.

Conclusion:
From the given options, the centrifugal pump (option B) represents an open thermodynamic system because it allows the transfer of both energy and matter across its boundaries. The other options either do not allow the exchange of matter (options a and d) or are completely closed systems (option c).

Open thermodynamic  system means exchange of energy(heat) as well as mass. (closed thermodynamic system means transfers only heat). here in centrifugal pump mass is water and energy is potential energy of water .so option b