Question

Adam Smith believed that the government should only have 3 basic responsibilities,

Answer 1

From this link

https://www.adamsmith.org/the-wealth-of-nations/

it reads : "For all these reasons, Smith believes that government itself must be limited. Its core functions are maintaining defence, keeping order, building infrastructure and promoting education"

So the answer in a short and simple way is: 

maintaining defence, keeping order, building infrastructure