A.I. Explanation:

Option 1: "a country's balance of trade is the main criteria of determining its economic prosperity."

Explanation: The text argues that exports and imports, along with a favorable balance of trade, do not serve as indicators of national prosperity. This directly contradicts the statement in Option 1, as it suggests that balance of trade is the main criterion, which the text refutes.

Option 2: "a nation's economy strengthens with the increase in exports."

Explanation: The passage indicates that despite a decrease in exports since the Second World War, England's national prosperity has increased. Therefore, this option is incorrect as it implies a direct correlation between exports and economic strength, which the text does not support.

Option 3: "english trade has continually increased since the Second World War."

Explanation: The text states that English exports were greater before the Second World War and have not increased since then. This makes Option 3 incorrect, as it falsely claims that trade has continually increased.

Option 4: "A country's economic standard can best be judged by its per capita income."

Explanation: The passage emphasizes that the income of average English workers has increased, indicating that per capita income is a better measure of economic prosperity than trade balance. This aligns with the main idea of the text, making Option 4 the correct answer.