Which of the following combinations should be selected for better tuning of an L.C.R. circuit used for communication?
A. $R = 25\Omega ,L = 1.5H,C = 45\mu F$
B. $R = 25\Omega ,L = 1.5H,C = 35\mu F$
C. $R = 25\Omega ,L = 2.5H,C = 45\mu F$
D. $R = 15\Omega ,L = 3.5H,C = 30\mu F$

Hint: Three crucial parameters and component elements that are of utmost concern in the alternating circuit are namely the inductance; capacitance and resistance [LCR].They are basically the most and vital parts of an alternating current circuit.

Complete step by step answer:
For a better output in the communication system, the resistance and conductance values must be considerably low while the inductance value must be high.
This will make the communication mechanism Seamless and uninterrupted.
This even most of the time helps a television and radio station to stick or be firm to its frequency.
$R = 15\Omega, L = 3.5H, C = 30\mu F$. As the resistance aspect of the circuit is concerned about the opposition to the flow of current within the circuit. The capacitance aspect has to do with the storage of charges developed in the circuit by the voltage sources; the value of capacitance is in microfarad which is a small unit of measurement and also resistance value of 15 ohms which is pretty small when compared with other values.
The practical unit of inductance is Henry which in this option is considerably high. Oftentimes there is always a need to solve for the Q-factor (quality factor) of the signals produced in the course of radio wave generation which also have a major effect on the circuit.
Except the option D, all the options have high resistances (although the value of resistance is less than inductance but for better communication it is considered high).
Therefore, the correct Option is Option D.

Note:A regular circuit of this type works best during communication and installation of an AC (alternating current circuit) system that requires inductance to resistance to capacitance ratio.