The answer is C. It is nonlinear because the increase in the “total house built” compared to the increase in the “months passed” does not show a constant rate of change.
ΔADB ≅ ΔCDB By Side-Side-Side (SSS) rule of congruency
ΔADB = ΔCDB By the definition of congruency
If the three sides of one triangle are congruent to the corresponding three sides of another triangle, then both triangles are said to be congruent according to the SSS rule of congruency