Meaning: 'Collected' means to gather or assemble items, in this case, sound samples from various sources.

Wrong options:

• herald: 'Herald' means to announce or proclaim, which does not fit the context of gathering samples.
• developed: 'Developed' implies creating or evolving something, which is not the action being described here.
• checkup: 'Checkup' refers to an examination or inspection, which does not relate to the action of gathering sound samples.

Correct answer: volcalizations

Explanation: The term 'volcalizations' is the correct choice as it refers specifically to sounds made by vocal organs, which aligns with the context of sound samples being studied.

Meaning: 'Volcalizations' refers to the sounds produced by animals, particularly their vocal sounds, which are relevant to the study of canine and human communication.

Wrong options:

• sameness: 'Sameness' refers to the quality of being the same, which does not apply to the types of sounds being analyzed.
• occupations: 'Occupations' refers to jobs or professions, which is unrelated to the context of sound samples.
• deformations: 'Deformations' refers to changes in shape or structure, which does not fit the context of vocal sounds.

Correct answer: undergoing

Explanation: The word 'undergoing' is appropriate here as it indicates that the subjects were in the process of receiving functional MRI scans, fitting grammatically and contextually with the sentence structure.

Meaning: 'Undergoing' means to experience or be subjected to something, in this case, the MRI scans.

Wrong options:

• conducting: 'Conducting' implies leading or managing an activity, which does not fit the passive context of receiving scans.
• attending: 'Attending' suggests being present at an event, which does not accurately describe the process of being scanned.
• examining: 'Examining' means to inspect or investigate, which does not fit the context of the subjects being scanned.

Correct answer: strongly

Explanation: The adverb 'strongly' fits well as it describes the intensity of the reaction of the brain area to vocalizations, aligning with the context of the sentence.

Meaning: 'Strongly' means with great intensity or force, indicating a significant reaction to the vocalizations.

Wrong options:

• foamy: 'Foamy' describes a texture and does not relate to the intensity of a reaction.
• deformatory: 'Deformatory' refers to causing deformation, which is irrelevant in this context.
• horny: 'Horny' typically refers to a sexual state or texture, which does not apply to the context of brain reactions.

Correct answer: responded

Explanation: The verb 'responded' is the correct choice as it indicates that the brain area reacted to the voices, fitting grammatically and contextually with the sentence structure.

Meaning: 'Responded' means to react or reply to something, in this case, the voices of other species.

Wrong options:

• splatted: 'Splatted' implies a messy impact, which does not fit the context of a brain's reaction.
• shoplift: 'Shoplift' means to steal from a store, which is completely unrelated to the context of brain responses.
• insulted: 'Insulted' means to offend or disrespect, which does not apply to the context of a brain's reaction to sounds.