Answer:
Explanation:
Expression for velocity of wave produced in a hanging wire can be given as follows
Velocity v = 
where T is tension in wire and m is mass of wire per unit length.
In the given case
T = Mg + mg
= Mg
neglecting weight of rope
mass of the rope per unit length
= m / L
Velocity of wave
= 
= 
B is the answer for your question the answer is b an elevator slowing down