Meaning: 'Whole' means complete or entire, suggesting that we have explored every part of the planet.

Wrong options:

• very: The word 'very' is an adverb that intensifies an adjective and does not fit the context of describing the planet as a complete entity.
• only: The word 'only' implies limitation, which contradicts the idea of encompassing the entire planet.
• total: While 'total' could imply completeness, it is typically used as a noun or adjective in a different grammatical structure, making it less suitable here.

Correct answer: so

Explanation: The word 'so' serves as a conjunction that connects the two clauses, indicating a logical consequence. It fits well in the context, suggesting that because of the advancements mentioned, we should know the number of countries.

Meaning: 'So' means 'therefore' or 'as a result,' indicating a conclusion drawn from the previous statement about global exploration and travel.

Wrong options:

• for: The word 'for' does not connect the clauses logically in this context, as it typically indicates purpose rather than consequence.
• while: The word 'while' suggests contrast or simultaneous actions, which does not fit the intended meaning of causation here.
• but: The word 'but' introduces a contrast, which is not appropriate in this context where a logical conclusion is being drawn.

Correct answer: Most

Explanation: The word 'Most' is appropriate as it refers to the majority of people, fitting grammatically and contextually within the sentence. It indicates that a significant number of people hold a particular belief about the number of countries.

Meaning: 'Most' means the majority or a large part of something, indicating that many people agree on the number of countries.

Wrong options:

• Few: The word 'Few' implies a small number, which contradicts the context of a majority opinion.
• All: The word 'All' suggests every person, which is too absolute and does not accurately reflect the varying opinions on the number of countries.
• Least: The word 'Least' indicates the smallest amount, which is contrary to the idea of a majority.

Correct answer: other

Explanation: The word 'other' fits grammatically as it refers to additional countries beyond those already recognized. It aligns with the context of discussing the recognition of countries, indicating that there are more than just the ones acknowledged.

Meaning: 'Other' refers to additional or different countries that are not included in the initial recognition, highlighting the complexity of international recognition.

Wrong options:

• those: The word 'those' is a demonstrative pronoun that refers to specific items, which does not fit the context of discussing countries in general.
• their: The word 'their' is a possessive pronoun that does not logically connect to the idea of recognizing countries.
• all: The word 'all' implies totality, which does not fit the context of recognizing additional countries that may not be universally acknowledged.