Final answer:
The most difficult task facing a marketing manager would be changing existing negative attitudes. So, the correct answer is option b.
Step-by-step explanation:
Of the given options, the most difficult task facing a marketing manager would be changing existing negative attitudes. This is because changing an individual's negative attitude towards a brand or product can be challenging and requires a strategic approach. It often involves overcoming preconceived notions, addressing past negative experiences, and providing strong evidence or testimonials to shift perceptions.
So, the correct answer is option b