Which of the following is NOT a valid Advantage of AC over DC?

Correct option is A

Negligible corona loss is not a valid advantage of AC over DC. 
 
Here are some advantages of AC over DC:
· Generation: AC is cheaper and easier to generate than DC. 
 
· Transmission: AC can be transmitted over long distances without much loss of electric power. 
 
· Efficiency: AC generators have higher efficiency than DC. 
 
· Voltage transformation: AC voltages can be readily transformed to higher or lower voltage levels. 
 
· Transformers: AC can be easily stepped up or down with a transformer. 
 
· Design: AC generators are more simple than DC generators. 
 
· Maintenance: AC generators are low maintenance devices. 
 
· Cost: AC generators have the lowest cost of ownership.