Option D: 5
IMA is Ideal Mechanical advantage, for pulley system it is equal to the number of ropes present in the system. At ideal conditions, it is equal to the number of times, input force is getting multiplied. For example, If a pulley uses two ropes, its required mechanical force to displace the load will be divided into two or the distance that should be pulled will be multiplied by two (keeping total energy constant).
In the pulley system in diagram, there are total of 5 ropes in the system that is total strand that lead directly to the load thus, IMA for this pulley system will be 5.