Fill in the blank with the correct preposition.
The employees rebelled __________ the manager.

against

The appropriate preposition to fill in the blank is against. The preposition against is used to indicate opposition or resistance. In this case, the employees rebelled against the manager, which means that they opposed the manager's authority.

The other options are incorrect.

• On is used to indicate location or position.
• At is used to indicate a specific point or place.
• With is used to indicate association or cooperation.