basically fibonachi is
the 1st term+term before first term=2nd term
3rd term=1st term+2nd term
4th term=2nd term+3rd term
etc
starting with t1=0 and t2=1
0,1
add them to get next
0+1=1
now we have
0,1,1
1+1=2
now we have
0,1,1,2
1+2=3
now we have
0,1,1,2,3
2+3=5
now we have
0,1,1,2,3,5
3+5=8
now we have
0,1,1,2,3,5,8
5+8=13
now we have
0,1,1,2,3,5,8,13
8+13=21
now we have
0,1,1,2,3,5,8,13,21
answer is A