Niko, I don't know what your choices are for filling in the blank, but I would say one of the following is true:
(A) Two regular hexagons are similar or
(B) Two regular hexagons are not similar.

"Similar" in geometry means they have exactly the same shape, although the sizes might differ. If the sizes and the shapes are identical, we also call the two "congruent".

Given what I said, do you think the right answer is (A) or (B)?

Stephen.