Proper phrasing for parents stating visit purpose at US Port of Entry

Hey everyone, logic check needed. My parents are flying in from India next month on B2 visas for a 4-week stay to visit me. I want to ensure their code—or rather, their story—is optimized for the Port of Entry. Is it safe for them to simply state “visiting son and tourism” as their primary purpose? I want to debug any potential issues before they arrive. Specifically, are there any phrases or topics they should absolutely avoid mentions of to prevent raising red flags with the immigration officer? Pushing for a smooth process here.

Realizing this is not about a visa application but the actual physical entry at the border, there is a specific protocol to follow.