You are given four ammeters A, B, C and D having the least counts mentioned below:
(a) Ammeter A with least count $0.25 \mathrm{A}$
(b) Ammeter B with least count $0.5 \mathrm{A}$
(c) Ammeter C with least count $0.05 \mathrm{A}$
(d) Ammeter D with least count $0.1 \mathrm{A}$
Which of the ammeters would you prefer for doing an experiment to determine the equivalent resistance of two resistances most accurately, when connected in parallel? 

Consider the two circuits A and B given alongside: 
In the circuits A and B shown here, the voltmeter reading would be:

                         (A)                                                                    (B)

The values of resistances marked on the coils $R_1$ and $R_2$ are found to be correct. A student connects the given resistors in the following manners (as shown in figure 1).

He then connects the terminals marked X and Y of the above combination of resistors R1 and R2 to the terminals marked X and Y in the circuit (shown in figure 2). The average value of the ratio $V/I$ in the observations recorded in the circuit would be:

Two students made two circuits A and B to determine the resultant resistance of two resistors $R_{1 }$and $R_2$ connected in series:

All the components have been connected correctly in:

Four students have made the following circuit diagrams for determining the equivalent resistance of two resistors connected in series:

The correct circuit diagram is:

Consider the following four circuits P, Q, R and S which have been set up to find the resultant resistance of two resistors combined in parallel:

The correct way of connecting the ammeter and voltmeter in the circuit is:

In order to determine the equivalent resistance of two resistors $R_1$ and $R_2$ connected in series, a student made this circuit for his experiment.

The only statement which is true for this circuit is that it gives:

To find the resultant resistance of two resistors when connected in series, a student arranged the various components according to the circuit shown alongside:
The student, however, did not succeed in his objective. Which of the following mistake has been made by the student in setting up the circuit?