Answer: D. Series circuits are simpler than parallel circuits.
Explanation:
In series circuit, all the components are connected in single path of current flow.
If one part of the circuit breaks, complete circuit would break and all the other parts also would not operate.
The voltage is not same everywhere. It is different across each component.
In series circuit, net resistance is more as resistance of all the components connected in series are added up.
So, the only advantage of a series circuit is that is simpler than the parallel circuits. Thus, the correct option is D.