Let`s assume the purchasing price of clock A is x.

According to the information given, clock B is purchased at a total cost of Rs. 650, so the purchasing price of clock B is 650 - x.

Clock A is sold at a 20% profit, which means the selling price of clock A is 1.2 times its purchasing price: 1.2x.

Clock B is sold at a 25% loss, which means the selling price of clock B is 0.75 times its purchasing price: 0.75(650 - x).

The problem states that the selling prices of both clocks are the same. So we can set up the following equation:

1.2x = 0.75(650 - x)

Let`s solve this equation to find the value of x:

1.2x = 0.75(650 - x)

1.2x = 487.5 - 0.75x

1.2x + 0.75x = 487.5

1.95x = 487.5

x = 487.5 / 1.95

x = 250

So the purchasing price of clock A is Rs. 250.

The purchasing price of clock B is 650 - 250 = Rs. 400.

Therefore, the correct answer is Rs. 250 for clock A and Rs. 400 for clock B.