Based on the liquid’s courses in the image, we must decide which cup will fill first.
It seems that many of the routes are blocked or impeded when looking at the construction of the pipes that lead to each cup.
Cup 1’s route is restricted.
Additionally, the route to cup two is obstructed.
Cup 4’s route is restricted.
The routes of Cups 5, 6, and 7 are either lengthy or blocked, and they are all found in branches farther down the system.
Cup 3 will fill quickest because it is the first one without any obstacles in its way.
Cup 3 is therefore the response.