Answer:
Option "SSS postulate" is correct.
Explanation:
Given that: Triangle NRM has legs m and n, and r is the length of its longest side.
and r² = m² + n².
Now, Ben constructed a right triangle EFD with legs m and n.
and in statement 4, it is proved that f=r.
So, all the three sides of the triangles NMR and EFD are congruent.
So, the triangles are congruent bt the SSS Postulate.
⇒ option "SSS postulate" is correct.