Concept:Currency depreciation is the general term for a fall in the value of one currency compared with other currencies.
Explanation:A country's currency can lose value against another currency in two main ways.
If the loss happens naturally through market forces, such as changes in demand and supply, it is known as depreciation.
If the government deliberately reduces the official value of the currency under a fixed exchange-rate system, that is called devaluation.
The question describes a simple fall and does not mention any government or official decision.
Therefore, the correct general term is depreciation.
"Reduction" is too vague, and "exchange rate" is the price of one currency in another currency, not the fall itself.
Answer:A. Depreciation