If you put in z to the equation

you get

and that equals 9 so the answer is B. 9
I^5 + i^6 + i^7 + i^8
i^11 + i^15
i^26
therefore your answer is:
i^26
Similar is the answer because no matter the transformation done to the figure it’s always going to be similar to the image(after transformation figure) not necessarily congruent but similar