What Is a Disadvantage of a Unitary System

What is a disadvantage of a unitary system?

A) Unitary systems are inefficient and tend to suffer from weak central leadership.
B) There is no competition between different political units in unitary systems, which can stifle policy development.
C) Unitary systems are autocratic, which often leads to rampant government corruption.
D) Unitary systems allow multiple parties to be included on the ballot, which can confuse voters.
E) Unitary systems have historically been plagued by weak national economies and high unemployment.