What is the correct way to brush your teeth?

The correct way to brush the external face of the teeth is with vertical sweeping movements, starting from the gum line and moving towards the free edge of the tooth.
The correct way to brush the internal face of the teeth is with a rotating wrist movement, starting from the gum line and moving towards the free edge of the tooth.
The correct way to brush the chewing surface of the teeth is with horizontal sweeping movements.
a) Only statement 1 is correct.
b) Only statement 2 is correct.
c) Only statement 3 is correct.
d) Statements 1, 2, and 3 are correct.