Answer:
subsititution
Step-by-step explanation:
Since in the situation it is mentioned that margot has fallen with 3 set bedroom i.e. 2500 square foot and its amount is $400,000. Now there is another three set bedroom of 2,400 square foot and its amount is $350,000 so here two options are given and according to the price he opted for the second property
So out of two choices he should opt for one that means it is a subsititution economic principle