The justification is: A. A linear pair is two adjacent, supplementary angles.
[tex]m \angle ABD $ and $ m\angle DBC[/tex] are complementary angles,
[tex]m \angle ABD + m\angle DBC = 90^{\circ}\\m \angle ABD + m\angle DBC = m \angle ABC \\[/tex]
Therefore:
[tex]m \angle ABC= 90^{\circ}[/tex]
[tex]\angle ABC $ and $ m\angle EBC[/tex] are two adjacent angles on a straight line.
Therefore:
[tex]\angle ABC + m\angle EBC = 180^{\circ}\\[/tex] (supplementary angles)
Substitute
[tex]90 + m\angle EBC = 180\\m\angle EBC = 180 - 90\\m\angle EBC = 90^{\circ}[/tex]
Therefore, the justification as to why [tex]m\angle EBC = 90^{\circ}[/tex] is: A. A linear pair is two adjacent, supplementary angles.
Learn more here:
https://brainly.com/question/10670714
