Final answer:
The effort required to lift a 100N load with a pulley system described would be 50N.
Step-by-step explanation:
To calculate the effort required to lift a 100N load using a pulley system where effort is half the load (Effort = Load / 2), you simply divide the load by 2. Therefore, the effort needed would be 100N / 2 = 50N. From the provided options, the correct effort required to lift the load is b) 50 N.