Step 1: Frequency of Balmer series lines.
The Balmer series of hydrogen has frequencies that follow a specific ratio. The second line of the series is \( \sim 1.35 \) times the first line.
Step 2: Conclusion.
Hence, the frequency of the second line is \( 1.35f \). Therefore, the correct answer is option (B).
Final Answer:
\[
\boxed{1.35f}
\]