Meaning: 'Balanced' means that the weights and pulleys are arranged in such a way that they work together evenly, preventing any tipping or instability.

Wrong options:

• accorded: 'Accorded' means to grant or bestow, which does not relate to the arrangement of weights and pulleys in this context.
• opposed: 'Opposed' suggests a conflict or resistance, which is contrary to the idea of a harmonious arrangement needed for the elevator's function.
• adjusted: 'Adjusted' implies a change or modification, but does not convey the necessary stability that 'balanced' does in this context.

Correct answer: introduced

Explanation: The word 'introduced' is appropriate as it indicates the arrival of steam and hydraulic elevators into the market, fitting grammatically and contextually with the timeline of elevator development.

Meaning: 'Introduced' means to bring something into use or operation for the first time.

Wrong options:

• announced: 'Announced' refers to making something known publicly, which does not fit the context of bringing elevators into practical use.
• offered: 'Offered' suggests making something available, but does not imply the formal introduction of a new technology as 'introduced' does.
• activated: 'Activated' means to make something active or operational, which does not accurately describe the process of bringing new elevator types to market.

Correct answer: installed

Explanation: The word 'installed' is the correct choice as it refers to the act of placing the first passenger elevator into operation, fitting both grammatically and contextually within the sentence.

Meaning: 'Installed' means to set up or put in place for use.

Wrong options:

• allotted: 'Allotted' means to distribute or assign, which does not fit the context of physically setting up an elevator.
• assigned: 'Assigned' implies giving a task or role, which is not relevant to the physical installation of an elevator.
• established: 'Established' suggests founding or creating something, but does not specifically refer to the act of setting up an elevator for use.

Correct answer: followed

Explanation: The word 'followed' is suitable as it indicates that the Era of the Skyscraper came after the advancements in elevator technology, fitting grammatically and contextually within the timeline of events.

Meaning: 'Followed' means to come after something in time or sequence.

Wrong options:

• resulted: 'Resulted' implies a cause-and-effect relationship, which does not accurately describe the chronological sequence of events.
• emulated: 'Emulated' means to imitate, which does not fit the context of a historical progression.
• composed: 'Composed' suggests being made up of parts, which does not relate to the sequence of events in this context.

Correct answer: design

Explanation: The word 'design' is appropriate as it refers to the plan or blueprint for the elevator, fitting grammatically and contextually within the discussion of elevator innovation.

Meaning: 'Design' means a detailed plan or drawing that outlines how something will be made or function.

Wrong options:

• sketch: 'Sketch' implies a rough or preliminary drawing, which does not convey the comprehensive nature of the elevator's design.
• diagram: 'Diagram' refers to a simplified drawing showing the appearance, structure, or workings of something, but lacks the broader implications of a complete design.
• draft: 'Draft' suggests a preliminary version of a document, which does not capture the finality and importance of the elevator's design.

Correct answer: world

Explanation: The word 'world' is fitting as it denotes a global presence and leadership in the industry, aligning grammatically and contextually with the description of Otis as a leader in building systems.

Meaning: 'World' refers to the global community or market, indicating the extensive reach and influence of Otis.

Wrong options:

• creation: 'Creation' refers to the act of making something, which does not fit the context of describing a leader in the industry.
• universe: 'Universe' implies a much broader scope than necessary, and does not specifically relate to the industry context.
• system: 'System' refers to a set of connected things or parts, which does not convey the idea of global leadership as effectively as 'world' does.