Answer:
Option B is the correct.
Step-by-step explanation:
In a series circuit, components are connected end-to-end in a line to form a single path through which current can flow.
In the diagram, option B and D, both are series circuits but circuit B has two resistors while circuit D has only one.
Circuit A and C are parallel circuits because their components are connected across each other's leads. They have many paths for current flow with one voltage across all components.
So, circuits A, C, and D are incorrect.