Read the passage about black rhinoceros populations in Africa, and then answer: genetically unique black rhinoceros populations have been lost in all of the following countries, except which one?

Introduction / Context:
This question comes from a reading passage describing how genetically unique populations of black rhinoceros have disappeared from many African countries. The passage then lists five countries where the species still survives. The phrase "all of the following countries, except" indicates that you must identify which option still has black rhinoceros populations and therefore did not lose them completely. This is a typical reading comprehension question that tests careful attention to lists and contrasts inside the text.

Given Data / Assumptions:
• The passage lists countries where black rhinoceros are now restricted: South Africa, Namibia, Kenya, Zimbabwe, and Tanzania. • It also lists countries where genetically unique populations once existed but have disappeared: Nigeria, Cameroon, Chad, Eritrea, Ethiopia, Somalia, Mozambique, Malawi, and Angola. • The options include Tanzania, Nigeria, Chad, and Malawi. • The question asks for the country where genetically unique populations have not been lost completely.

Concept / Approach:
The passage clearly separates current range countries from former range countries where unique populations have been lost. The best strategy is to identify which of the options appears in the list of current range countries rather than the list of countries that have lost these populations. The word "except" signals that three options will belong to the lost list and only one will belong to the current range list. This reversal often confuses students, so you must read slowly and maybe underline both lists in the original passage.

Step-by-Step Solution:
1. Locate in the passage the sentence that says the species is now restricted to five countries. 2. Note the five countries: South Africa, Namibia, Kenya, Zimbabwe, and Tanzania. 3. Next, locate the sentence that lists countries where genetically unique populations have disappeared. 4. Note that Nigeria, Cameroon, Chad, Eritrea, Ethiopia, Somalia, Mozambique, Malawi, and Angola are in that lost list. 5. Compare the options with these two lists. 6. Observe that Nigeria, Chad, and Malawi are explicitly part of the disappeared list, whereas Tanzania is part of the current range list.

Verification / Alternative check:
To verify, you can quickly classify each option: Nigeria is in the disappeared group, Chad is also in the disappeared group, and Malawi is again named as a country where genetically unique populations have vanished. Only Tanzania appears among the countries where black rhinoceros are still found today. Since the question asks for the exception, Tanzania must be the correct choice. If you reverse the logic and ask, "In which of these countries do black rhinoceros still survive," the answer would again be Tanzania, confirming the result.

Why Other Options Are Wrong:
Option B, Nigeria, is named as a country where genetically unique populations that once existed have disappeared. Option C, Chad, is again listed among those where such populations have vanished. Option D, Malawi, is also in the same lost group in the passage. Since the question asks for the country which has not lost its genetically unique black rhinoceros populations, all three of these are incorrect. They are examples of the problem that the passage is highlighting rather than exceptions to it.

Common Pitfalls:
Many learners ignore the small but critical word "except" and accidentally choose a country where loss actually occurred. Another common error is mixing up current range countries with the list of countries that have lost their populations, especially when reading quickly. To avoid these mistakes, it helps to underline or mentally separate lists when reading passages full of names and numbers. Paying attention to contrast words like "but today", "however", and "disappeared" also helps in identifying how the author organises information.

Final Answer:
Genetically unique black rhinoceros populations have been lost in Nigeria, Chad, and Malawi, but they still survive in Tanzania.