To answer this question, we need to identify the country that matches the given description.
The capital city mentioned is Khartoum, which is the capital of Sudan. Sudan is located in north-eastern Africa.
Let's go through each option to understand why it is correct or incorrect:
Option A) Chad - This option is incorrect because the capital of Chad is N'Djamena, not Khartoum.
Option B) Uganda - This option is incorrect because the capital of Uganda is Kampala, not Khartoum.
Option C) Ethiopia - This option is incorrect because the capital of Ethiopia is Addis Ababa, not Khartoum.
Option D) Sudan - This option is correct because the capital of Sudan is Khartoum, which matches the given information.
Therefore, the correct answer is D) Sudan.