Yes, D is the correct answer. The ammeter reads 9 Amps, and that current is flowing down, away from the intersection.
The reason is simple, and I'm sure you must have learned it somewhere along the way:. The sum total of all the currents INto any point in a circuit is equal to the total of the current OUT of the same point. In other words: The sum total of the current building up at any point in a circuit is ZERO.
Why ? Current is a river of electrons. If there's more current arriving at a point or leaving it, then you need something there that can create new electrons, store them, destroy them, or eat them.
The picture shows 5+7=12A arriving at the intersection, so you need 12A leaving that point. 3A + the ammeter reading = 12A.
Got it now ?