The formula used: For RC circuit the time constant is

Where t is the time constant

R is the resistance

C is the capacitance

Frequency

Then the frequency of the RC circuit is given by

For LR circuit the time constant is given by

Where is the time constant

L is the inductance

R is the resistance

Then the frequency is given by

Let’s take a multiplication of f1 and f2

This combination has a dimension of frequency.

The above combination has a dimension of frequency

i. RC has a frequency component

ii. LR has a frequency component

iii. f1f2 has a frequency component

Thus, option A, B and C are correct.