Meaning: 'Generate' means to produce or create something, in this case, an identification tag.

Wrong options:

• success: 'Success' is a noun that does not fit grammatically as it cannot follow 'was to' in this context.
• find: 'Find' is a verb that does not convey the intended meaning of creating something new, making it unsuitable here.
• sample: 'Sample' is a noun that does not fit grammatically in this context, as it does not align with the action of creating an identification tag.
• extracted: 'Extracted' is a past participle that does not fit the grammatical structure required after 'was to.' It also does not relate to the action of creating an identification tag.

Correct answer: stretch

Explanation: The word 'stretch' is a noun that fits grammatically as it describes a portion of DNA. Contextually, it refers to the segment of DNA used for identification, making it the correct choice.

Meaning: 'Stretch' refers to a continuous length or extent of something, in this case, a segment of DNA.

Wrong options:

• success: 'Success' is a noun that does not describe a part of DNA and does not fit grammatically in this context.
• generate: 'Generate' is a verb that does not fit as it does not describe a segment of DNA, making it unsuitable here.
• find: 'Find' is a verb that does not relate to the context of describing a portion of DNA, thus it is incorrect.
• sample: 'Sample' is a noun that could refer to a part but does not specifically indicate a segment of DNA, making it less precise than 'stretch.'
• extracted: 'Extracted' is a past participle that does not fit grammatically or contextually as it does not describe a part of DNA.

Correct answer: extracted

Explanation: The word 'extracted' is a past participle that fits grammatically as it describes the action of obtaining DNA. Contextually, it aligns with the ease of obtaining DNA from mitochondria, making it the correct choice.

Meaning: 'Extracted' means to remove or obtain something from a source, in this case, DNA from mitochondria.

Wrong options:

• success: 'Success' is a noun that does not fit grammatically or contextually as it does not describe an action related to obtaining DNA.
• find: 'Find' is a verb that does not convey the action of obtaining DNA and does not fit the context here.
• sample: 'Sample' is a noun that does not fit grammatically as it does not describe the action of obtaining DNA.
• generate: 'Generate' is a verb that does not fit in this context as it does not relate to the action of obtaining DNA from a source.