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>
 
        
        
        
The two most common units of electric energy is Watts or hertz.
        
             
        
        
        
There is no definite end to earths atmosphere, but technically the border between the outer space and earth gets thinner as you move up from the earths surface. The Karman line is the closest definition there is which describes the end of the earth's atmosphere, it is 100 km above earth's sea level at approximately 1.56 % of total earth's radius. This describes the boundary between the outer space and the atmosphere.
        
             
        
        
        
Sodium, magnesium, and aluminum! 
        
                    
             
        
        
        
Electricity is NOT a part of electromagnetic spectrum.
An electromagnetic spectrum contains electromagnetic radiations arranged according to frequencies and wavelength.
<h2>Further Explanation
</h2><h3>Electromagnetic waves  </h3>
- Electromagnetic waves are types of waves that do not require a material medium for transmission. 
- These waves are mostly transverse in nature, which means the direction of transmission is perpendicular to the direction of vibration of particles.
- They include, light waves, radio waves, x-rays, infra-red, etc.
<h3>Electromagnetic spectrum
</h3>
- An electromagnetic wave shows electromagnetic waves arranged according to frequencies and wavelength.  
- Electromagnetic spectrum contains electromagnetic waves: Gamma rays, x-rays, Ultraviolet, Visible light, infra-red, microwaves, and radio waves.
- The electromagnetic spectrum is divided into various sections based on wavelength, with gamma rays having the shortest wavelength and radio waves having the longest wavelength. 
- The part of the electromagnetic spectrum that we can see using our naked eyes is called the visible light spectrum.
- In order of frequency, the radio waves have the lowest frequency while gamma rays have the largest frequency.
<h3>General characteristics of electromagnetic waves  </h3>
- They travel with the speed of light (3.0 x 10^8 m/s)
- They possess energy that is given by; E =hf, where h is the plank’s constant and f is the frequency.
- They are transverse in nature, and therefore, the wavelength is measured between successful crests or troughs.
- They can travel through vacuum
Keywords: Electromagnetic spectrum, electromagnetic waves.
<h3>Learn more about:  </h3>
Level: High school  
Subject: Physics
Topic: Electromagnetic spectrum