Organisms change over time. Some of these changes make no difference to the success or failure of the organisms that inherit them; other changes do. Take a group of antelopes in which one individual has longer legs than its siblings. Those longer legs make the individual better at escaping from predators, hence giving it an advantage in the survival stakes. Its descendants inherit this feature and are better able to survive as a consequence. Those longer legs have thus become an 'adaptation'. Their evolution means that this particular lineage of antelopes has adapted to its conditions, thanks to its development of this feature.
Over the generations, the individual components of the genetic code within a species change, or mutate. So far as we know, mutations may provide no evolutionary advantage at all. They may be disadvantageous, in which case they are weeded out via natural selection; or they may be advantageous, in which case they persist through the generations.
What happens to disadvantageous mutations?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → They are removed through natural selection
The passage says that mutations may be disadvantageous, "in which case they are weeded out via natural selection". To weed out means to remove what is unwanted; such mutations are removed through natural selection.
Why the Other Options are Incorrect?
Option 2: They persist through the generations — Incorrect. Wrong link: it is the advantageous mutations that persist through the generations.
Option 3: They remain an additional burden on the species — Incorrect. Contradicted: disadvantageous mutations do not remain; they are weeded out.
Option 4: None of the above — Incorrect. Contradicted: Option 1 states what the passage says.