Answer:
Arithmetic, 5
Explanation:
Arithmetic sequences mean that the previous number has a common difference, where it may be added or subtracted by a common difference to get the next number in the sequence. In this situation, the common difference is 5, so you add 5 to 4 to get 9. You also do this to 9, add 5 and you get 14.
You can see the common difference by just subtracting the next term by the previous one. If the difference varied throughout the sequence, then it is not arithmetic, chances are it's geometric