Is the one i picked right

The arithmetic sequence formula should help you
An= A1+ (n-1)d or An= a + d(n−1)
An= the term that you want to find.
A1 = first term in the list of ordered numbers
n = the term position (ex: for 5th term, n = 5 )
d = common difference of any pair of consecutive or adjacent numbers
So, looking the 4 choices you have the only one that follow the sequence of the formula is C
I believe the one you choose is Fibonacci sequence.
There different number of sequences:
1- arithmetic sequence
2- geometry sequence
3- Fibonacci sequence
Each of that sequences have their own formula.
So, the answer it might be C
Hope that help you

The formula for the Arithmetic is:
An = A1 + F x ( n- 1)
I believe answer is C
Because the one you chose is

8-2x+3x2=6 and six is your answer