Read the passage about black rhinoceros and genetic lineages in sub Saharan Africa, and then answer: over the last two hundred years, how many black rhinoceros genetic lineages have been lost?

Introduction / Context:
This question checks your ability to extract a specific numerical detail from a reading passage about conservation biology. The passage describes how many distinct genetic lineages of the black rhinoceros once existed in sub Saharan Africa and how many remain today. From this information, you must calculate the number of lineages that have been lost over approximately two centuries. Such questions combine careful reading with basic arithmetic, and they are very common in competitive examinations.

Given Data / Assumptions:
• Two centuries ago, black rhinoceros in sub Saharan Africa had 64 different genetic lineages. • At present, only 20 genetic lineages remain. • The question asks for the number of lineages that have been lost, not the number remaining. • Loss is calculated as original number minus current number.

Concept / Approach:
The approach is straightforward: identify the two key numbers mentioned in the passage and then compute the difference. You must be careful not to confuse the number of lineages that remain with the number lost. A reading trap is that one of the answer options simply repeats each of the numbers from the passage. Therefore you must perform the subtraction 64 minus 20 and choose the correct result. This type of question tests both precise reading and accurate use of basic arithmetic operations.

Step-by-Step Solution:
1. From the passage, note that there were 64 different genetic lineages two centuries ago. 2. Also note that only 20 genetic lineages remain today. 3. Understand that the number of lineages lost is equal to original lineages minus remaining lineages. 4. Perform the subtraction: 64 minus 20. 5. Compute 64 - 20 = 44. 6. Match this result with the answer choices and locate "44 genetic lineages".

Verification / Alternative check:
A quick check is to reason whether the answer seems realistic: if 64 lineages existed and only 20 survive, more than half must have been lost. Half of 64 is 32, so the loss must be greater than 32. That eliminates numbers like 20 and 30. Since 44 is greater than 32 and the difference calculation supports it, it is a sensible answer. You can also recheck the subtraction by reversing it: 20 remaining plus 44 lost equals 64 original, which confirms that the arithmetic is correct.

Why Other Options Are Wrong:
Option A, 64 genetic lineages, is the original number and does not represent the loss. Option B, 20 genetic lineages, is the current number remaining, not the number lost. Option D, 30 genetic lineages, is a distractor that might tempt someone who subtracts incorrectly or works only roughly. None of these values equal the difference between 64 and 20. Only option C correctly represents the number of lineages that have disappeared over the two hundred year period.

Common Pitfalls:
Students sometimes misread the question and directly pick a number that is explicitly mentioned in the passage, forgetting that the task requires a calculation. Another common error is to reverse the subtraction and compute 20 minus 64, which would give a negative number that does not make sense in this context. To avoid such mistakes, always restate the question in your own words, such as "How many are missing now compared to the original number", and then set up the calculation accordingly.

Final Answer:
The number of black rhinoceros genetic lineages lost over two centuries is 44 genetic lineages.