Answer:
a. for both restaurants to abide by the cartel’s agreement.
Step-by-step explanation:
As per the given situation, the most profitable outcome i.e. combined for the two restaurants is that the both restaurant should be abide via cartel agreement as in the both cases the earnings is $80,000 so this represent the most profitable condition for these two restaurants
Hence, the option a is correct
And, the rest of the options are wrong