The expression:
3 (x - 2)
indicates that the number 3 before the parenthesis is multiplying the expression inside the parenthesis.
Then in order to do such we use what is called the distributive property which tells us to "distrubute" suche multiplication among the two term that are in the parenthesis:
3 x - 3 * 2
3 x - 6
Which is the first option in your answer list.