Meaning: 'Occasion' means a particular time or instance of an event, suggesting that volunteers put themselves in danger during specific situations.

Wrong options:

• situation: While 'situation' refers to a set of circumstances, it lacks the nuance of a specific event, making it less suitable in this context.
• event: 'Event' is too broad and does not convey the same sense of a specific instance as 'occasion' does, making it less precise here.
• moment: 'Moment' implies a brief period of time and does not capture the sense of a significant event, thus not fitting well in this context.

Correct answer: called

Explanation: The word 'called' is the correct choice as it indicates being summoned or requested to act, which fits the context of rescue operations. It is grammatically correct and aligns with the urgency of the situation.

Meaning: 'Called' means to be summoned or requested to do something, particularly in an emergency, which is relevant to the context of rescue teams responding to climbers in need.

Wrong options:

• pulled: 'Pulled' suggests a physical action rather than a request for assistance, making it inappropriate in this context.
• summoned: While 'summoned' is similar, it carries a more formal connotation that does not match the conversational tone of the passage.
• required: 'Required' implies necessity but lacks the active sense of being called to action, making it less fitting in this context.

Correct answer: debt

Explanation: The word 'debt' is appropriate here as it conveys a sense of obligation or gratitude owed to the rescue teams. It fits grammatically and contextually, emphasizing the appreciation climbers feel towards those who help them.

Meaning: 'Debt' in this context refers to a moral obligation to be grateful, indicating that many climbers feel they owe thanks to the rescue teams.

Wrong options:

• recognition: 'Recognition' implies acknowledgment but does not convey the same depth of obligation as 'debt', making it less suitable here.
• liability: 'Liability' refers to legal responsibility, which does not fit the context of gratitude and appreciation being expressed.
• claim: 'Claim' suggests a demand or assertion, which does not align with the sentiment of gratitude intended in this context.

Correct answer: involved

Explanation: The word 'involved' is the correct choice as it indicates the costs that are part of maintaining the service. It fits grammatically and contextually, suggesting that these costs are integral to the operation of rescue teams.

Meaning: 'Involved' means included or part of something, indicating that there are costs that are necessary for the functioning of the rescue teams.

Wrong options:

• implied: 'Implied' suggests something that is suggested but not directly stated, which does not fit the context of discussing actual costs.
• featured: 'Featured' implies being highlighted or showcased, which does not relate to the costs associated with maintaining a service.
• connected: 'Connected' suggests a relationship but does not convey the direct involvement of costs in the operational context.

Correct answer: donations

Explanation: The word 'donations' is the most fitting choice as it refers to contributions given voluntarily, which is essential for the rescue teams' operations. It aligns well with the context of public support and financial assistance.

Meaning: 'Donations' refer to gifts or contributions, typically of money, given to support a cause, which is crucial for the rescue teams' functioning.

Wrong options:

• grants: 'Grants' are funds given for specific purposes, often with conditions, which does not capture the voluntary nature of support implied here.
• allowances: 'Allowances' refer to regular payments or provisions, which do not fit the context of voluntary contributions for rescue operations.
• aids: 'Aids' generally refer to assistance or support but lacks the specificity of financial contributions that 'donations' conveys.