A person placed on an extension of 25 lights that are placed in a series circuit, the extension stops functioning when one or more of the 25 lights are going bad. The extension stops working and a person examines it and informs them that it has four fused (bad) lights, but does not tell them where they are. The person takes four new lights (that works) to replace the bad four, decides to do it at random, and removes four of the 25 lights and replaces them.
A. In how many different ways could that person select the four 4 lights of the extension that he is going to replace?
B. In how many different ways could that person select the four 4 lights he will replace so that none of the four 4 that are selected are fused?
C. In how many different ways could that person select the four 4 lights he will replace so that only two of those four 4 are fused?
D. What is the probability that the person will operate the extension after selecting four 4 lights at random and replacing them with new lights?