"between the two countries"
A prepositional phrase needs to contain a preposition, in this case it would be "between". As well it needs to modify the sentence and it should mention the object of the sentence. So "between the two countries" is correct.
Answer:
NONE of these sentences is written correctly.
Explanation:
corrections:
A. While Jonathan was napping, I finished doing the dishes. (the word 'while')
B. Although the lasagna looked terrible, it tasted wonderful. (the word 'although')
C. Ever since I was a teenager, I have loved going to the theater. (the word 'I')
D. Pepper and I decided it was time to head home. (the word 'decide')
