If collusion were not illegal, then it would be
more optimal
a. for Megastore to advertise and for
Superstore to advertise.
b. for Megastore to advertise and for
Superstore not to advertise.
c. for Megastore not to advertise and for
Superstore to advertise.
d. for Megastore not to advertise and for
Superstore not to advertise.