4. Put the user on ignore and pretend that nothing is happening, which is the easiest option, but for me personally, it is also the worst because then nothing will change for sure.
Ignore the users who is having the only intention of trolling and for that ignore option is really helpful but to tackle spammers report to moderators should be the tool, and if the user is having this as habit then eventually they will be in the risk of getting temp banned at least for multiple deleted reports for spam as reason.