In a series circuit, all devices are constrained to a single flow of current. There can only be a single value for the current for all devices, otherwise this would violate the conservation of charge. Therefore the current must be the same across each resistor.
In a series circuit, two or more resistors are connected in a line. The equivalent resistance of the circuit is greater than any individual resistor. As more resistors are added, the current decreases. The voltage across each resistor is different. The current remains same across the circuit.
Option B would be right one according to momentum conservation 6600*2 = 13200kgm/s 5400*3 = 16200kgm/s 16200-13200 = 3000 now 6600-5400 = 1200 kg thus 3000/1200 = 2.5 v
