Which triangle must be a right triangle and why?

Answer:Option 4 is correct: ΔBGC is right angle because line EG ⊥ line segment CC'.Step-by-step explanation:Right Angled triangle is triangle with measure of one angle 90°.Option A: ΔA'B'C' is not right traingle because no angle if of 90° and image has no role in it. It only work if ΔABC is also a right angle traingle but it is not.Option B: Intersection of line/line segment has no role in right triangle if it does not intersect at right angle. ∴ ΔADC is not right angled triangle.Option C: ΔBCC' is not right angled triangle because thee is not right angle and point B lies on line of reflection has no role in it.Option D: ΔBGC is right angle triangle because m∠BGC = 90°.m∠BGC = 90° as line EG is perpendicular to CC' at G.Option D is correct.