A Difference Between Maslow's Need Hierarchy and Alderfer's ERG Theory

A difference between Maslow's need hierarchy and Alderfer's ERG Theory is that:

A) ERG theory states that various needs operate simultaneously.
B) Maslow's hierarchy has more scientific validity.
C) Maslow's hierarchy states that once a need is satisfied, it acts as a powerful motivator.
D) ERG theory focuses on five levels of need.
E) ERG theory reminds managers of the types of reinforcers that can be used to motivate people.