Meaning: 'Destructive' means causing great damage or harm.

Wrong options:

• estimate: 'Estimate' is a verb that does not fit as it cannot describe weather; it refers to calculating or judging the value or number of something.
• starvation: 'Starvation' is a noun that refers to suffering or death caused by lack of food, which does not relate to describing weather.
• stable: 'Stable' is an adjective that means not likely to change or fail, which contradicts the context of severe weather events.

Correct answer: worth

Explanation: The term 'worth' is a noun that indicates the value of the damage caused by the EI Nino. It fits grammatically as it follows the possessive form 'pounds'' and contextually as it quantifies the financial impact of the disaster.

Meaning: 'Worth' refers to the value of something, in this case, the monetary damage caused.

Wrong options:

• estimate: 'Estimate' is a verb that does not fit in this context as it cannot quantify damage directly; it refers to the act of calculating.
• starvation: 'Starvation' is a noun that does not relate to financial value and is irrelevant in this context.
• destructive: 'Destructive' is an adjective and cannot function as a noun to indicate value.

Correct answer: strike

Explanation: The verb 'strike' is used here to indicate that the 1990 EI Nino will occur or hit. It fits grammatically as it is in the future tense and contextually as it refers to the anticipated impact of the EI Nino event.

Meaning: 'Strike' means to hit or occur suddenly, often used in the context of natural disasters.

Wrong options:

• estimate: 'Estimate' is a verb that does not convey the sudden occurrence of an event and is not appropriate in this context.
• starvation: 'Starvation' is a noun that does not relate to the action of an event occurring and is irrelevant here.
• stable: 'Stable' is an adjective that does not indicate an action and contradicts the context of an impending event.

Correct answer: completely

Explanation: The adverb 'completely' modifies the adjective 'sure' to indicate the extent of certainty regarding the causes and effects of EI Nino. It fits grammatically as it enhances the meaning of 'sure' and contextually as it reflects the uncertainty surrounding the phenomenon.

Meaning: 'Completely' means fully or entirely, indicating a lack of doubt.

Wrong options:

• estimate: 'Estimate' is a verb that does not fit as it cannot modify 'sure' and does not convey certainty.
• starvation: 'Starvation' is a noun that does not relate to certainty and is irrelevant in this context.
• stable: 'Stable' is an adjective that does not fit as it does not convey the degree of certainty needed in this sentence.