I need help asap please help me I just can't figure it out!!

Question 1(Multiple Choice Worth 2 points) (02.04 MC) Triangle ABC is shown below: D B E A C Given: AABC Prove: All three angles of AABC add up to 180. The flowchart with missing reason proves the measures of the interior angles of AABC total 180:Prove: All three angles of AABC add up to 180*. The flowchart with missing reason proves the measures of the interior angles of AABC total 180: EBC = BCA Alternate Interior Angles maBCA + mxCBA + mxBAC = 180* 4DBA = 4BAC Substitution DE || AC Alternate Interior Angles by Construction m EBD = 180* Definition of a Straight Angle mxEBC + mxCBA + mxDBA = 180" Substitution mxEBC + mxCBA + mxDBA = mxEBD Which reason can be used to fill in the numbered blank space? OAssociative Property of Addition O Triangle Exterior Angle Theorem OAngle Addition Postulate O Commutative Property of Addition