Option 1 -> "contrary to" suggests opposition, which doesn't logically connect launching a campaign with declining sales.
Option 2 -> "in response to" indicates the campaign was a reaction to address the declining sales problem.
Option 3 -> "instead of" would illogically suggest the campaign replaced the declining sales rather than addressing them.
Option 4 -> "though" is a conjunction that doesn't grammatically fit or convey the cause-and-effect relationship needed here.
Hence, Option 2: in response to -> This phrase correctly establishes that the aggressive marketing campaign was launched as a direct reaction to tackle the problem of declining sales, showing a logical cause-and-effect relationship between the business problem and the company's action -> correct