Meaning: 'Stable' means not likely to change or fluctuate, indicating that the percentage of left-handed people stays constant.

Wrong options:

• even: 'Even' suggests equality or uniformity but does not convey the idea of consistency over time, making it contextually inappropriate here.
• continual: 'Continual' implies something that happens repeatedly over time, which does not accurately describe the static nature of the percentage mentioned.
• similar: 'Similar' indicates likeness but does not imply stability or consistency, thus failing to fit the context of the sentence.

Correct answer: run

Explanation: The verb 'run' is used here to indicate that handedness is a trait that can be observed or passed down through generations, fitting grammatically and contextually with the subject of families.

Meaning: 'Run' in this context means to occur or be present, particularly in relation to genetic traits within families.

Wrong options:

• happens: 'Happens' is too informal and does not convey the genetic transmission aspect as effectively as 'run' does.
• is: 'Is' is a linking verb that does not provide the action or occurrence implied in the context of handedness being passed down.
• occurs: 'Occurs' is similar to 'happens' but lacks the specific connotation of genetic transmission that 'run' provides.

Correct answer: function

Explanation: The word 'function' fits grammatically as it refers to the role or purpose of the brain, aligning well with the context of discussing brain activities and their importance.

Meaning: 'Function' refers to the specific activities or roles that the brain performs, such as processing language and thought.

Wrong options:

• memory: 'Memory' is a specific aspect of brain function but does not encompass the broader concept of how the brain operates as a whole.
• size: 'Size' refers to the physical dimensions of the brain and does not relate to its operational capabilities.
• capacity: 'Capacity' suggests the potential or ability of the brain but does not directly address the active roles it performs.

Correct answer: significant

Explanation: The word 'significant' is appropriate as it indicates a noteworthy or considerable number, fitting grammatically and contextually with the discussion of left-handed individuals and their language dominance.

Meaning: 'Significant' means important or large enough to be noticed, highlighting the relevance of the number of left-handers with varied language dominance.

Wrong options:

• maximum: 'Maximum' implies the greatest possible amount, which does not fit the context of discussing a noteworthy number.
• suggestive: 'Suggestive' indicates something that implies or hints at something else, which does not accurately describe the quantity being discussed.
• countable: 'Countable' refers to something that can be counted but does not convey the importance or relevance of the number in this context.

Correct answer: searching

Explanation: The word 'searching' fits grammatically as it indicates an active pursuit of knowledge or information, aligning with the context of scientists looking for links to conditions related to left-handedness.

Meaning: 'Searching' means actively looking for or investigating, which is appropriate for the context of scientific inquiry.

Wrong options:

• researching: 'Researching' is a more formal term but does not fit as well in the context of the sentence, which implies a broader search rather than a focused study.
• detecting: 'Detecting' suggests finding something that already exists, which does not align with the proactive nature of the inquiry implied.
• inquiring: 'Inquiring' is similar to searching but is less commonly used in scientific contexts, making it less suitable here.