Concept:The system is a simple pendulum oscillating about a fixed point.
The middle of the swing is the lowest point of the motion.
Explanation:At the middle of the swing, the mass is at its lowest vertical height.
Gravitational potential energy depends on height, so it is minimum here.
Thus statement i is correct.
At the lowest point, the speed of the mass is maximum.
Kinetic energy depends on speed, so it is maximum at the middle of the swing.
Thus statement ii is correct.
Ignoring air resistance and friction, no external work is done on the system.
Mechanical energy, which is the sum of potential and kinetic energy, is conserved.
Therefore, the total energy remains constant throughout the swing.
Thus statement iii is correct.
Since all three statements are valid, the correct option is A.
Answer:A. i, ii and iii