1. The problem asks for the difference between the highest and lowest marketing campaign reach percentages for Poland. 2. The reported percentages for Poland are 80%, 65%, 49%, and 35%. 3. Identify the highest percentage: $\max(80,65,49,35) = 80$. 4. Identify the lowest percentage: $\min(80,65,49,35) = 35$. 5. Calculate the difference: $$80 - 35 = 45$$. 6. Therefore, the difference between the highest and lowest reach percentages in Poland is 45%. 7. The correct answer is 45%.