What is the rule to find the value of the missing term

Answer:
Option (B)
Step-by-step explanation:
The position numbers are being multiplied by three to get the value of the term.
1 * 3 = 3
2 * 3 = 6
3 * 3 = 9
4 * 3 = 12
and
n * 3 = 3n
Option B should be the correct answer.
Brainilest Appreciated.