Answer:
C
6/13
Explanation:
Comment
This is not a true sequence. It just has the same things done to the numerator as to the denominator.
The numerator (top part of the fraction).
Add 3 to the previous numerator's top
So 3 + 3 = 6 which is the numerator of the second term.
15 + 3 = 18 which is the numerator of the seventh term.
So the numerator of the 4th term is 9 + 3 = 12
The Denominator
The difference there is 5
So 21 + 5 = 26
The answer is
12/26
This reduces down to 6/13