A speculative attack on a fixed exchange rate is likely to occur when:Group of answer choicesa devaluation is expectedthe government imposes capital controlsa revaluation is expectedthe exchange rate is undervalued

A speculative attack on a fixed exchange rate is likely to occur when a devaluation is expected.

Here's the step by step explanation:

1. A fixed exchange rate is a regime where the official exchange rate is fixed to another currency or to a basket of currencies.

2. Speculative attack refers to a situation where traders believe that a currency is overvalued and therefore, they sell off the currency in anticipation of it falling and buy it back after it has fallen.

3. If traders expect a devaluation of the currency, they would sell off the currency in anticipation of this. This is because if the currency is devalued, it will be worth less compared to other currencies.

4. Therefore, by selling off the currency before it is devalued, traders can avoid losses that would result from the decrease in value of the currency.

5. This selling off of the currency can lead to a speculative attack on the fixed exchange rate, as the increased supply of the currency on the foreign exchange market can put downward pressure on the exchange rate, potentially causing it to fall below the fixed rate.

6. The other options (the government imposes capital controls, a revaluation is expected, the exchange rate is undervalued) are less likely to lead to a speculative attack. For example, if a revaluation is expected or the exchange rate is undervalued, traders would be more likely to buy the currency in anticipation of it increasing in value, rather than selling it off.

A speculative attack on a fixed exchange rate is likely to occur when a devaluation is expected.

Here's the step by step explanation:

1. A fixed exchange rate is a regime where the official exchange rate is fixed to another currency or to gold.

2. Speculative attack refers to a situation where traders believe that a currency is overvalued and therefore, they sell off the currency in anticipation of the currency's fall.

3. When a devaluation is expected, it means that the value of the currency is expected to decrease in terms of other currencies.

4. In such a situation, traders would want to sell off the currency before the devaluation occurs to avoid losses. This selling pressure can lead to a speculative attack on the currency.

5. Therefore, a speculative attack on a fixed exchange rate is likely to occur when a devaluation is expected.

The other options do not lead to a speculative attack. Capital controls are measures to control the flow of foreign capital into and out of the domestic economy, a revaluation is an increase in the value of a currency, and an undervalued exchange rate means that the value of the currency is low compared to other currencies, which does not incentivize a speculative attack.