Match the columns.

i-b, ii-a, iii-d, iv-c

The correct answer is option 2. i-b, ii-a, iii-d, iv-c.

Here is an explanation of the matching between the instruments and their functions:

i. Voltmeter - This instrument is designed to measure voltage, which is the electrical potential difference between two points in a circuit. Voltmeters are connected in parallel with the component or circuit whose voltage is to be measured.

ii. Ammeter - An ammeter is used to measure the magnitude of electric current flowing through a circuit. It is connected in series with the circuit component through which the current is to be measured.

iii. Galvanometer - A galvanometer is a sensitive instrument used to detect and measure small electric currents. It can measure both the direction and magnitude of the current. Galvanometers are often used as the basis for ammeters and voltmeters.

iv. Ohmmeter - An ohmmeter is specifically designed to measure the electrical resistance of a component or circuit. It typically works by passing a known current through the component and measuring the voltage drop across it, then using Ohm's law (V=IR) to calculate the resistance.

So, the correct match is i-b, ii-a, iii-d, iv-c. Each instrument is paired with its respective function based on its design and intended use in electrical measurements.