Explanation
The series consists of 20 positions with 9 blanks at the odd-numbered positions: 3, 5, 7, 9, 11, 13, 15, 17, and 19. By sequentially placing the letters from option b) into these blanks, we get the following complete sequence:
f h [g] h [h] g [f] h [g] g [h] h [f] f [g] g [h] h [g] f
To identify the pattern, we can look at the letters at the odd-numbered positions (1, 3, 5, 7, 9, 11, 13, 15, 17, 19):
f, g, h, f, g, h, f, g, h, g
This represents a repeating cycle of the letters f, g, and h (f-g-h, f-g-h, f-g-h) followed by the next letter in the cycle, g.
When looking at the even-numbered positions (2, 4, 6, 8, 10, 12, 14, 16, 18, 20), the sequence is:
h, h, g, h, g, h, f, g, h, f
The resulting sequence of letters placed in the blanks is g-h-f-g-h-f-g-h-g, which follows a clear repetitive structure of g-h-f twice, followed by g-h-g. This completes the series in a consistent manner.