Meaning: 'Surveyors' are individuals who measure land and determine its boundaries.

Wrong options:

• locals: 'Locals' refers to people from the area, which does not fit as they are not the ones establishing the mountain's height.
• joke: 'Joke' is a noun that does not relate to the action of establishing a fact about the mountain.
• surprise: 'Surprise' is a noun that does not fit as a subject performing the action of establishing.
• truth: 'Truth' is a noun that does not fit grammatically as it cannot perform the action of establishing.

Correct answer: surprise

Explanation: The word 'surprise' fits as a noun that describes the unexpected nature of the fact that Mount Everest was the highest mountain. It maintains grammatical coherence as it follows the verb 'came as' and aligns with the context of an unexpected revelation.

Meaning: 'Surprise' refers to an unexpected event or fact.

Wrong options:

• locals: 'Locals' does not fit as it refers to people and does not convey the sense of an unexpected event.
• joke: 'Joke' does not fit contextually as it does not relate to the unexpected nature of the fact.
• surveyors: 'Surveyors' is a noun that does not convey the sense of an unexpected event or fact.
• truth: 'Truth' does not fit as it does not convey the sense of surprise or unexpectedness.

Correct answer: illusion

Explanation: The term 'illusion' fits grammatically as a noun that describes the perception of Mount Everest among other peaks. It aligns with the context of discussing how Peak XV appeared compared to other mountains, suggesting a deceptive appearance.

Meaning: 'Illusion' refers to a false perception or belief about something.

Wrong options:

• locals: 'Locals' does not fit as it refers to people and does not describe a perception or appearance.
• joke: 'Joke' does not fit contextually as it does not relate to the perception of the mountain.
• surveyors: 'Surveyors' is a noun that does not describe a perception or appearance.
• truth: 'Truth' does not fit as it does not convey the idea of a deceptive appearance.

Correct answer: height

Explanation: The word 'height' fits as a noun that describes the measurement of how tall something is, which is relevant in the context of comparing Mount Everest to other peaks. It maintains grammatical coherence and aligns with the discussion of the mountain's stature.

Meaning: 'Height' refers to the measurement of how tall something is.

Wrong options:

• locals: 'Locals' does not fit as it refers to people and does not relate to the measurement of mountains.
• joke: 'Joke' does not fit contextually as it does not relate to the measurement of height.
• surveyors: 'Surveyors' is a noun that does not describe a measurement or comparison of height.
• truth: 'Truth' does not fit as it does not convey the concept of measurement.