The word "static" would be known to be friction as air rushing against an airplane
Lower resistivity means higher conductivity: among these materials, the best conductor is silver, therefore it must be the material with lowest resistivity among those. We can also have a look at the value of resistivity of the different materials listed in the problem, to check our answer. The resistivities of the materials are the following:
Wood:

Salt water:

Silver:

Lead:

<span>We see that the material with lowest resistivity among those is silver, therefore the correct answer is silver.</span>
Answer:
Option a)
Explanation:
In the process of charging anything by the method of induction, a charged body is brought near to the body which is neutral or uncharged without any physical contact and the ground must be provided to the uncharged body.
The charge is induced and the nature of the induced charge is opposite to that of the charge present on the charged body.
So when a positively charged rod is used to charge an electroscope, the rod which is positive attracts the negative charge in the electroscope and the grounding of the electroscope ensures the removal of the positive charge and renders the electroscope negatively charged.
The change in the gravitational potential energy is represented by the equation
u = ΔPE = Δmgh
since the mass of the system will remain constant and the acceleration due to gravity will also remain constant, the equation will become
u = mg Δh