We have appealed to him again and again; there is no use flogging a dead horse now. Here 'flogging a dead horse' means?

Beating about the bush

Repeating our request

Wasting time in useless effort

None of these

The idiom "flogging a dead horse" means trying to continue with something that has no hope of success.

In this context, it suggests further appeals are pointless and a waste of time.