1) A person of unknown age drinking a beer
2) A person clearly in their 40s drinking a clear liquid
3) A person clearly under 18 drinking a clear liquid
4) A person of unknown age drinking tea
Assuming that where I have said something is known, you don't need to check it (e.g. the beer is really beer and the tea is really tea), which people must you check to make sure the law is being obeyed?