Step 1: Analyse options.
- The series follows two rules simultaneously:
1. The number of bars increases by one in each step ($1 \rightarrow 2 \rightarrow 3$).
2. The entire group of bars shifts one position to the right in each step.
- The fourth figure must therefore contain four bars, shifted one additional position to the right from the third figure.
Step 2: Conclusion.
Figure B correctly displays four bars in the shifted position.
Final Answer: (b) B