Notice that the distribution of the vertices of the figure is the same, in other words,
B' is in 'the same position' with respect to A' and C' as B is with respect to A and C.
Therefore, neither reflection nor rotation can be the answer.
Thus, the answer is translation, option C
i’m pretty sure the answer is 3
21 divided by 7 equals 3
Divide 18 by 3 and you get 3 as an answer