The sequence is: C4X, F9U, I16R, ?
Analyzing the first letter pattern:
C = 3rd letter of alphabet
F = 6th letter of alphabet
I = 9th letter of alphabet
The position increases by 3 each time: 3, 6, 9, 12
The 12th letter is L
Analyzing the number pattern:
4 = 22
9 = 32
16 = 42
The next term is 52=25
Analyzing the last letter pattern:
X = 24th letter of alphabet
U = 21st letter of alphabet
R = 18th letter of alphabet
The position decreases by 3 each time: 24, 21, 18, 15
The 15th letter is O
Combining all patterns:
First letter: L
Number: 25
Last letter: O
Therefore, the missing term is L25O.
The answer is Option 4: L25O