Respuesta :
For a better understanding of the solution provided here please find the relevant diagram drawn as per given information in the file attached.
As given, [tex]\angle ABC=90^{\circ}[/tex]. Also, it is given that [tex]\angle DBC[/tex] is a straight angle. Therefore, [tex]\angle DBC=180^{\circ}[/tex].
As can be clearly seen from the diagram, if [tex]\angle DBC=180^{\circ}[/tex] and [tex]\angle ABC=90^{\circ}[/tex], then:
[tex]\angle ABD=\angle DBC-\angle ABC=180^{\circ}-90^{\circ}=90^{\circ}[/tex]
Therefore, [tex]\angle ABD\cong\angle ABC[/tex]
Hence Proved.

Answer: C. definition of congruent angles
Step-by-step explanation:
I took the test and get it right.