Priming of a centrifugal pump is done to

Answer: Option B

The correct answer is Option B: Develop effective pressure rise by the pump.
Here's why:
Priming a centrifugal pump means filling the pump casing and suction pipe completely with the liquid to be pumped *before* starting the pump.

Why is this important?
If the pump casing is filled with air or gas, the impeller (the rotating part) will mostly just churn the air.
Centrifugal pumps need to be filled with liquid to work correctly.

Let's look at the other options:
* Option A: Increase the mass flow rate of fluid: Priming doesn't directly increase the flow rate once the pump is running, but is a prerequisite for pumping to commence.
* Option C: Avoid chances of separation inside the impeller: While cavitation (separation) *can* be worsened by improper priming, the *primary* reason for priming is to create an initial pressure head.
* Option D: None of these: This is incorrect since priming does have a specific purpose.

Therefore, the main reason for priming is to remove air and create a liquid-filled environment so the impeller can effectively develop pressure and begin pumping.