The correct answer is: Only conclusion II follows.
The statement says that all political prisoners who had gone to jail for reasons other than political dharnas were released on bail. It also says that bail was not granted to persons involved in murders.
Conclusion I states that no political prisoner had committed murder. This conclusion does not follow from the statement. The statement only says that bail was not granted to persons involved in murders. It does not say that no political prisoner had committed murder. It is possible that some political prisoners had committed murder, but were not granted bail for other reasons.
Conclusion II states that some politicians were not arrested. This conclusion does follow from the statement. The statement says that all political prisoners who had gone to jail for reasons other than political dharnas were released on bail. This means that some political prisoners must have gone to jail for reasons other than political dharnas. It is possible that these political prisoners were not arrested for political reasons.
Therefore, only conclusion II follows.