Select the reason why these triangles are similar. If they are not, select "Not similar".
A. AA
B. SAS
C. SSS
D. Not similar

The reason why these triangles are similar is;

A. AA

Step-by-step explanation:

A two column proof can be presented using the drawing of the question diagram created with Microsoft Visio as follows;

Statement                        Reason

║                        Given

∠ACB ≅ ∠DCE               Vertically opposite angles

∠BAC ≅ ∠DEC               Alternate interior angles theorem

∠ABC ≅ ∠CED               Alternate interior angles theorem

ΔABC ~ ΔCDE                 By Angle-Angle (AA) similarity postulate

Therefore, the correct option is AA.