Answer:
The capacitance per unit length is 
(b) is correct option.
Explanation:
Given that,
Radius a= 2.50 mm
Radius b=7.50 mm
Dielectric constant = 3.68
Potential difference = 120 V
We need to calculate charge per length for the capacitance
Using formula of charge per length

Put the value into the formula


We know that,

We need to calculate the capacitance per unit length
Using formula of capacitance per unit length



Hence, The capacitance per unit length is 
The correct anwser is in deep soil or anoxic aquatic sediment.
"Frequency" just means "often-ness" ... how often something happens.
It's always expressed as
<em>(number of happenings) / (some period of time) .</em>
It's actually Friction.
I just did the test and got it right.