In Bohr series of lines of hydrogen spectrum, the third line from the red end corresponds to which one of the following inter-orbit jumps of the electron for Bohr orbits in an atom of hydrogen?

The correct option is B $5\to 2$
For visible spectrum i.e., Balmer series $n_2=2.$ Transition from $3\to 2$ corresponds to line with lowest energy i.e., in red region. Therefore, transition from $5\to 2$ corresponds to third line from red end.