Answer:The pair of angles must be supplementary are ∠2 and ∠5.
The correct option is (B)
What is supplementary angle?
Two angles are called supplementary when their measures add up to 180 degrees.
Given that:
∠2=90 and ∠5=90
So,
∠2+∠5
=90+90
=180
Hence, angle 2 and 5 makes supplementary angles.