Explanation

Reading the question: If and when we get confused by this prompt or any prompt, we can start with the simplest part and work from there. We'll use this approach in Reading Comprehension. For example, "exploiting economies in driving routes" may be unclear, but delivering on seven days rather than six is clear. So we start with increased delivery time. That tends to be less cost effective, because of some details about how the deliveries are done, but the company "expects profits to rise with the change."

Creating a filter: We could treat this as an explain question, but here's a little trick: When we have an argument that profits will go up, we can break it into two logical pieces: i) revenues go up and/or ii) costs go down. In this case, the delivery cost is not going down--could the new model bring down some other cost (probably not)? Or increase revenues (more likely)?

We apply the filter, looking for some other cost going down, or revenues going up. Choice (A) doesn't give us that; it's good news for the retailer, but this change has already taken effect, so it's already built into the "before" part of the "before-and-after" comparison that the company is making. Choice (B) gives us what we're looking for: it describes increased revenues, and even revenues that exceed costs. Choice (B) passes the filter. Choice (C) does not give us a rising revenue or lowering cost. Choice (D) is similar to (A), but inferior, because this retailer could have more customers without making more revenue, or they might make a little more revenue but not enough to profit more. Choice (E) basically says there are no one-time costs to the shift, but that doesn't explain why the difference between revenues and costs will increase with the change; it still could be less profitable over time after change on a marginal basis.

Logical proof: if we accept the negation of (B), then consumer purchases will not increase sufficiently to increase profits. That fact would highly damage the argument, so (B) itself, indeed, supports the argument. The correct answer is (B).