Within one year, that country has … its currency five times.

Analyze the question: The sentence is about a country changing the value of its currency five times in one year. We need the verb that fits "currency" and describes a drop in its official value.

Explain the concept: In economics, to devalue a currency means to officially lower its value relative to other currencies, such as the dollar. This is a common word in Nigerian news and economics, for example "the CBN devalued the naira."

Check each option:

• A. reduced – You can reduce prices or quantity, but "reduced its currency" is not the standard expression. It is vague and does not mean lowering the currency's exchange value.
• B. devalued – Correct. It is the precise term for lowering a currency's value.
• C. revamped – This means to renovate or improve something's structure, such as a system or a building. It does not suit "currency" here.
• D. defaced – This means to spoil the surface of something, like writing on a banknote. Doing that five times in a year by a whole country makes no sense.

Solution: The sentence becomes: "Within one year, that country has devalued its currency five times." The meaning is clear and the collocation "devalue a currency" is standard.

Answer: B. devalued.

Tip: In "lexis and structure" questions, look for collocations, words that naturally go together. "Currency" pairs with devalue, depreciate, appreciate and revalue. Also note the prefix de- meaning "down", as in devalue (lower the value).