You can say all of the above😊 But what works best is : “I am good thank you “ is polite and formal and works for formal and informal conversations

Thank you for your answers!

It's definitely not a must! "I am good" is one of the many ways you can reply to that question:)

You can say I’m fine, or I’m ok, or I’m good, or alright. Either phrase would be ok.

There are a lot of common ways to answer this question, such as: - I'm great - I'm very good - I'm doing well - Not bad - I'm pretty good/well - I'm fairly good/well - I'm really good/well - Never been better And many more. Nevertheless you can still improvise, change the common options in your own way, come out with your own answers or even say something about how you really are, dependently on who you talk to.