Actually, although 'farthest' is uncommon in abstract context, 'farthest' and 'furthest' are interchangeable (according to the Oxford Dictionary of English).
Farther and further are comparative adverbs or adjectives. They are the irregular comparative forms of far. We use them to talk about distance. There is no difference in meaning between them.
Although some usage guides insist that only farther should be used for physical distance (We walked farther than we planned), farther and further have been used interchangeably throughout much of their histories. However, only further is used in the adverbial sense "moreover'' (Further, you hurt my feelings) and in the adjectival senses "more extended'' (no further comment) and "additional'' (Further bulletins came in).
I knew that Paraguay was landlocked, but for some reason I typed Uruguay. African Countries and Mid East Asia countries were easily visualized as being for from water, especially the "stans". Burkina Faso; for some reason I thought it was on the coast, next to Ivory Coast. Loved this quiz!
Nice quiz! This is also about the first time that I've looked at the list of most popular answers and it's been roughly the order in which I thought of them.
https://koryogroup.com/blog/stan-countries-a-story-of-seven-stans#:~:text='Stan'%20means%20'place%20of,It's%20like%20England%20or%20Scotland.
So basically 'land'.
Farther and further are comparative adverbs or adjectives. They are the irregular comparative forms of far. We use them to talk about distance. There is no difference in meaning between them.
Although some usage guides insist that only farther should be used for physical distance (We walked farther than we planned), farther and further have been used interchangeably throughout much of their histories. However, only further is used in the adverbial sense "moreover'' (Further, you hurt my feelings) and in the adjectival senses "more extended'' (no further comment) and "additional'' (Further bulletins came in).