Which of the following combinations should be selected for better tuning of an LCR circuit used for communication?
1. R=20 Ω, L=1.5 H, C=35 μF
2. R=25 Ω, L=2.5 H, C=45 μF
3. R=15 Ω, L=3.5 H, C=30 μF
4. R=25 Ω, L=1.5 H, C=45 μF

(c) Hint: The quality factor should be high for better tuning.
Step 1: Quality factor (Q) of an L - C - R circuit is given by,
 Q=1RLC
where R is resistance, L is the inductance and C is the capacitance of the circuit.
Step 2: To make Q high, L should be high and C should be low.
These conditions are best satisfied by the values given in option (c).