Answer:
For the first one, its B) cities B and C
I'm not so sure, but I hope this helps.
 
        
             
        
        
        
The answer is underground
        
                    
             
        
        
        
Answer:
a)  R = ρ₀ L /π(r_b² - R_a²)
, b)  ρ₀ = V / I    π (r_b² - R_a²) / L
Explanation:
a) The resistance of a material is given by
           R = ρ l / A
where ρ is the resistivity, l is the length and A is the area
the length is l = L and the resistivity is ρ = ρ₀
the area is the area of the cylindrical shell
            A = π r_b² - π r_a²
            A = π (r_b² - r_a²)
we substitute
          R = ρ₀ L /π(r_b² - R_a²)
b) The potential difference is related to current and resistance by ohm's law
          V = i R
           
we subsist the expression of resistance
           V = I ρ₀ L /π (r_b² - R_a²)
            ρ₀ = V / I    π (r_b² - R_a²) / L
 
        
             
        
        
        
Answer:
b. craters, river valleys feeding into surface lakes of very cold liquids 
Explanation:
- Jovian moons are the four largest satellites like the moon of the Jupiter ie the Lo, Europa, Ganymede, Callisto and were first seen by the galileo. They are amiugly the largest moons with radii larger than the dwarf planet.  
- Lo has more than 400 active volcanoes and dotted more than 100 mountains and has an extremely thin atmosphere made up of sulfur dioxide. The Europa has deep oceans of liquid water, and the layer of ice, and are characteristic of the tidal heating.   
- <u>While the surface of Callisto is heavily cratered and has salty liquid water.</u>
 
        
             
        
        
        
Answer:
In general solids are easier to transport than liquids, but the above metal example is a valid one and the only other one that comes to mind is that of concrete. It is mixed as a liquid and transported as such, but then sprayed or laid down to dry and form a solid surface or filler. 
Explanation: