C1L, F4O, I9R, L16U, ?

Options

A. O 25 X
B. N 25 Z
C. O 20 X
D. N 16 Z

Answer

A

Explanation

`C overset(+3) to F overset(+3) to I overset(+3) to L overset(+3) to O`
`I overset(+3) to 4 overset(+5) to 9 overset(+7) to 16 overset(+9) to 25`
`L overset(+3) to Q overset(+3) to R overset(+3)to U overset(+3)to X`
`therefore ? = O 25 X`