B
Opposites attract
Like poles repel
Answer:
The current flows through the insulator is 2 mA.
Explanation:
Given that,
Resistance 
Voltage = 200 kV
We need to calculate the current
Using ohm's law


Where, I = current
V = voltage
R = resistance
Put the value into the formula



Hence, The current flows through the insulator is 2 mA.
I think your talking about refraction and if so the first medium it existed in before entering the second usually has the higher speed especially it the first medium is less denser than the second
Answer: Some challenges that I could see would be the walls, possibly a moat, tar, and the towers.
Explanation: The wall is obliviously a main problem, trying to get over it or through it is a difficult challenge. The moat (if it has one) means that there is more than likely only one way to get in or out. If it does have tar it means that the attackers are going to be put in a "sticky situation" And finally the towers, they have people at the top shooting arrows down at you, or throwing things at you.