Answer:
A chain
Step-by-step explanation:
A series circuit is a circuit, where the resistors are arranged in a chain. They are aligned like this so the current only has one path to take. The current quantity is the same through each resistor.
If you ever have trouble remembering this you can think of a movie series which goes on and on and on. And remembering a parallel circuit is simpler because everything in the circuit will be parallel!