If Hannah visits a combined total of four cities in countries X and Y, what is the greatest total number of days she ...

Hello, I am not sure why the answer is 8. Although in the video explanation Y can have been visited 3 cities. According to the rule, Hannah visits at least one city in each country. Y3 and X1 6. 2. I am not sure why the answer is not 6. (Wouldn't answer choice 8 violate the rule above? Would this indicate that X does not get visited by Hannah then?)