Which one of the following substances has infinitely high electrical resistance?
A- conductor
B- Insulator
C- Superconductors
D- Resistor

Hint: when electrons move through anybody then they feel some opposition. This opposition is due to the collision of the electrons with the ions of the host body. During these collisions’ energy is lost in the form of heat as it is evident the wire through which current passes becomes hot. This opposition to the flow of the current is called the resistance.

Complete step by step answer:
We can classify substances as conductors, insulators and semiconductors. There is one more category called superconductors. Conductors are those substances through which current passes through ease without any appreciable loss of energy in the form of heat or light. So, conductors have very low resistance.
Superconductors are a class of substances when the temperature falls to a certain minimum threshold then the resistance becomes zero and the substance behaves as a superconductor. For example below 4 degree Celsius, mercury behaves as a superconductor. They have zero resistance.
The substance which falls in the category of semiconductors have conductivity greater than the insulator but lesser than the conductors. For example, silicon and germanium
Insulators are a class of substance which does not allow the flow of current through them and as such they offer infinite resistance to the flow of electrons through them.

So, the correct answer is “Option B”.

Note:
Resistors are not but created pieces of wires which have resistance of known values and they are extensively used in the laboratories. The resistance is the property of the substance and it varies a little with the change in temperature and pressure except for superconductors which shows a drastic reduction in the resistance under suitable conditions of temperature and pressure.