The correct answer is option 2: 7, 6, 8, and 2. This means that national highway A is labeled as 7, national highway B is labeled as 6, national highway C is labeled as 8, and national highway D is labeled as 2.

It`s important to note that the labeling of national highways is not arbitrary and follows a standardized numbering system. The numbering system varies from country to country, but in this particular case, the given map uses a specific numbering scheme.

To fully understand the correct answer, let`s evaluate the other options:

Option 1: 6, 8, 7, and 12. This contradicts the correct answer because highway D is labeled 12 instead of 2. Therefore, option 1 is incorrect.

Option 3: 8, 2, 7, and 6. This is the exact reverse of the correct answer. The labeling of the national highways is in the reverse order compared to option 2. Therefore, option 3 is incorrect.

Option 4: 2, 6, 7, and 8. This is also the reverse order of the correct answer. The labeling of the national highways from A to D is in