C. depends on the components
D. depends on the source e.m.f
I had been asked this question in an interview.
The origin of the question is Limitations of Wheatstone Bridge topic in section Measurement of Resistance of Electrical Measurements
To elaborate: As the resistance must have a tolerance of upto 1%, cost of maintenance of the Wheatstone bridge circuit is expensive. Voltage source does not add to the cost of maintenance of a Wheatstone bridge as it is uniform for all bridge circuits.