A statement and portions of the flowchart proof of the statement are shown.

Which reason should appear in the box labeled 1?


Angle Addition Postulate

Angle Congruence Postulate

Ruler Postulate

Linear Pair Postulate
Flow chart proof. Given measure of angle B A C is 20 degrees and measure of angle C A D is 15 degrees. Prove the measure of angle B A D is 35 degrees. Given image shows acute triangle A B D. Point C is on side B D with point C slightly closer to point D. Segment A C drawn. Flow chart consisting of 4 rows of horizontal text boxes. A horizontal line segment joins the midpoints of each of the vertical sides of each of the text boxes effectively subdividing each text box into an upper box and lower box. In row 1 there is 1 textbox. In the upper half of the box is the equation the measure of angle B A D equals the measure of angle B A C plus the measure of angle C A D. In the lower half of the box is the number 1 in a smaller box. In row 2 there are 2 text boxes. In the upper half of the box on the left is the equation the measure of angle B A C equals 20 degrees. In the lower half of the box is the word Given. In the upper half of the box on the right is the equation the measure of angle C A D is 15 degrees. In the lower half of the box is the word Given. In row 3 there is 1 text box. In the upper half of the box is the equation the measure of angle B A D equals 20 degrees plus 15 degrees. In the lower half of the box is the phrase Substitution Property of Equality. In row 4 there is 1 text box. In the upper half of the box is the equation the measure of angle B A D equals 35 degrees. In the lower half of the box is the word Simplify. A ray is drawn from the text box in row 1 to the text box in row 3. A ray is drawn from each of the text boxes in row 2 to the text box in row 3. A ray is drawn from the text box in row 3 to the text box in row 4.