This is my first answer on brainly so forgive me if I'm wrong but I believe the answer is B.
D. when it tries to sell you products related to your obvious interests
Answer:
The one, if true, that most seriously weakens the argument is "Many customers of Colson's are expected to do less shopping there than they did before the Spend Less store opened."
Explanation:
The argument of this excerpt states that all of the stores that are in the district will close within the next 5 years and that they will be fastly substituted by new ones, but it is highly probable that this time it will happen differently since the new store is going to be the direct competence not to the small stores but Colson's the big department store.