Meaning: 'Search' means to look for something or someone, often with a specific goal in mind, which in this case is adventure.

Wrong options:

• chase: 'Chase' implies pursuing something that is moving away, which does not fit the context of seeking adventure as it suggests a more aggressive action.
• seek: 'Seek' is a synonym of 'search,' but it is less commonly used in this context and does not fit the grammatical structure as smoothly as 'search.'
• hunt: 'Hunt' typically refers to pursuing animals for sport or food, which does not align with the more general concept of seeking adventure.

Correct answer: ultimate

Explanation: The word 'ultimate' is the most appropriate choice as it conveys the idea of being the best or most significant, which fits the context of describing the balloon trip as the highest challenge.

Meaning: 'Ultimate' means the best or most extreme of its kind, indicating that the balloon trip is considered the pinnacle of adventure challenges.

Wrong options:

• extreme: 'Extreme' suggests a high degree of something but does not convey the sense of being the best or final as 'ultimate' does.
• utmost: 'Utmost' refers to the greatest degree or amount but is less commonly used to describe challenges compared to 'ultimate.'
• eventual: 'Eventual' implies something that will happen at some point in the future, which does not fit the context of describing a challenge.

Correct answer: reach

Explanation: The verb 'reach' is the correct choice as it indicates arriving at a destination, which is appropriate for the context of getting to the North Pole.

Meaning: 'Reach' means to arrive at or attain a particular place or goal, in this case, the North Pole.

Wrong options:

• meet: 'Meet' typically refers to coming into the presence of someone or something, which does not fit the context of traveling to a location like the North Pole.
• attain: 'Attain' implies achieving something after effort, but it is less commonly used in the context of physical locations compared to 'reach.'
• fulfil: 'Fulfil' means to complete or satisfy a requirement, which does not fit the context of traveling to a geographical location.

Correct answer: achievement

Explanation: The word 'achievement' is the best fit as it refers to something accomplished, particularly through effort, which aligns with the context of David's significant accomplishment.

Meaning: 'Achievement' means a thing done successfully, typically by effort, which in this case refers to reaching the North Pole in a hot-air balloon.

Wrong options:

• recognition: 'Recognition' refers to acknowledgment or validation, which does not fit the context of describing a significant accomplishment.
• acquisition: 'Acquisition' implies gaining possession of something, which does not align with the context of an accomplishment in the same way as 'achievement.'
• realisation: 'Realisation' refers to the act of becoming fully aware of something, which does not fit the context of describing a significant accomplishment.

Correct answer: involved

Explanation: The word 'involved' is appropriate as it indicates that the distance and altitudes are part of the challenge, fitting grammatically and contextually with the sentence structure.

Meaning: 'Involved' means to be a part of or connected with something, which in this case refers to the distance and altitudes being part of the challenge.

Wrong options:

• engaged: 'Engaged' typically refers to being occupied or involved in an activity, but it does not fit the context of describing distance and altitudes as part of a challenge.
• regarded: 'Regarded' implies having a particular opinion about something, which does not fit the context of describing the relationship of distance and altitudes to the challenge.
• connected: 'Connected' suggests a link but does not convey the same sense of being part of the challenge as 'involved' does.