Just plug in 3 for n and then 5 for n to see if an turns out to be 10 and 26.
n=3:
A) an = 8*3+10 = 34
B) an = 8*3 - 14 = 10 OK
C) an = 16*3+10 = 58
D) an = 16*3 - 38 = 10 OK
n=5:
B) an = 8*5-14 = 26 OK
D) an = 16*5 - 38 = 42
So the answer is B
Sh*t i had the answer but i lost my train of thought sorry :(
if there's 1 boy to every 4 girls, there's going to be 5 boys for every 20 girls