List additional examples of countries separated by physical, geometric, or ethnic boundaries (on the chart below).

Borders are imaginary lines that divide a nation, state, province or city from others. These dividing lines can be taken from geographic features, such as rivers, seas, lakes, mountains, etc .; or in geometric form, using lines as meridians and parallels; or for ethnic reasons, dividing populations based on languages, ethnic origin, etc.

Examples of each of these types of border are:

-Natural border between Argentina and Chile along the Andes Mountains, taking as the dividing line the highest point of the same.

-Geometric border between America and Canada on the west coast, taking the line of parallel 49 as division.

-Ethnic border between Pakistan and India, dividing both nations according to concepts of Islamic or Hindu religious affiliation.

d is the logical answer but im not a 100% sure