A.I. Explanation:

Correct answer: until

Explanation: 'Until' indicates a point in time leading up to an event, which fits grammatically and contextually as it introduces the timeframe for the flourishing of formal sign languages.

Meaning: 'Until' means 'up to the time of' and is used to denote a limit in time before something happens.

Wrong options:

• from: 'From' indicates the starting point of a time period, which does not align with the context of when formal sign languages began to flourish.
• onto: 'Onto' suggests movement towards a surface or position, which is not relevant in this temporal context.
• at: 'At' refers to a specific point in time but does not convey the sense of duration leading up to an event, making it unsuitable here.

Correct answer: emerged

Explanation: 'Emerged' indicates the beginning or coming into existence of institutions for the deaf, fitting well both grammatically and contextually within the sentence.

Meaning: 'Emerged' means to come into view or existence, highlighting the establishment of institutions for the deaf.

Wrong options:

• declined: 'Declined' means to decrease or diminish, which contradicts the idea of institutions coming into existence.
• converged: 'Converged' implies coming together from different directions, which does not accurately describe the establishment of new institutions.
• repaired: 'Repaired' suggests fixing something that is broken, which is not relevant to the context of institutions being formed.

Correct answer: unique

Explanation: 'Unique' describes the distinct identity of American Sign Language, aligning grammatically and contextually with the idea of it having its own characteristics.

Meaning: 'Unique' means being the only one of its kind, emphasizing the individuality of ASL compared to other sign languages.

Wrong options:

• necessary: 'Necessary' implies something that is essential, which does not fit the context of describing identity.
• primary: 'Primary' suggests being the first or most important, which does not accurately reflect the concept of identity in this context.
• common: 'Common' indicates something that is widespread or usual, which contradicts the idea of ASL having a distinct identity.

Correct answer: path

Explanation: 'Path' refers to a course or direction taken, which fits grammatically and contextually as it describes the journey of sign languages through history.

Meaning: 'Path' means a way or track laid down for walking or made by continual treading, metaphorically representing the journey of sign languages.

Wrong options:

• exploration: 'Exploration' refers to the act of searching or investigating, which does not fit the context of a journey or course.
• subject: 'Subject' refers to a topic or area of discussion, which is not relevant to the context of a journey.
• signal: 'Signal' implies a sign or indication, which does not convey the idea of a journey or course taken.

Correct answer: witnessed

Explanation: 'Witnessed' indicates that something was observed or experienced, fitting well grammatically and contextually as it describes the resurgence of sign languages.

Meaning: 'Witnessed' means to see or experience an event, highlighting the recognition of sign languages as complex systems.

Wrong options:

• mentored: 'Mentored' implies guidance or teaching, which does not fit the context of observing a resurgence.
• gained: 'Gained' suggests acquiring something, which does not accurately describe the act of observing a resurgence.
• distributed: 'Distributed' means to spread out or hand out, which is not relevant to the context of witnessing a resurgence.