I assume you mean the equation
Since i = √(-1), we have i⁴ = 1 and so i⁵ = i. Then 2x + 3 must be some multiple of 5.
Now just check for which of the given choices that this holds:
x = 16 ⇒ 2x + 3 = 35 (yes)
x = 11 ⇒ 2x + 3 = 25 (yes)
x = 10 ⇒ 2x + 3 = 23 (no)
x = 14 ⇒ 2x + 3 = 31 (no)
