Match List - I with List - II.

List-I	List-II
(A) AC generator	(I) Detects the presence of current in the circuit
(B) Galvanometer	(II) Converts mechanical energy into electrical energy
(C) Transformer	(III) Works on the principle of resonance in AC circuit
(D) Metal detector	(IV) Changes an alternating voltage for smaller or greater value

We need to match the devices in List-I with their descriptions in List-II.

(A) AC Generator:

An AC generator converts mechanical energy (rotation of the coil in a magnetic field) into electrical energy (alternating current). This matches (II).

(B) Galvanometer:

A galvanometer is a device used to detect the presence and direction of current in a circuit. This matches (I).

(C) Transformer:

A transformer is used to step up or step down an alternating voltage, i.e., it changes an alternating voltage to a smaller or greater value. This matches (IV).

(D) Metal Detector:

A metal detector works on the principle of resonance in an AC circuit. When a metal object is brought near the coil, it changes the impedance and disturbs the resonance condition. This matches (III).

Therefore the correct matching is: A - II, B - I, C - IV, D - III.

The correct answer is Option A: A - II, B - I, C - IV, D - III.