The correct option is C 9:4
The energy of the nth state of the single electron system is given by,
En=(Z2n2)(−13.6 eV)
For Hydrogen atom Z=1.
As for first excited state, n2=2 and for second excited state, n3=3
⇒E2E3=(n3n2)2=(32)2=94
Hence, option (C) is correct.