Malthus’s theory was influential for a long time. But it was also challenged by theorists who claimed that economic growth could outstrip population growth. However, the most effective refutation of his theory was provided by the historical experience of __________. 

European countries

The correct answer is Option 1: European countries

NCERT: "Malthus’s theory was influential for a long time. But it was also challenged by theorists who claimed that economic growth could outstrip population growth. However, the most effective refutation of his theory was provided by the historical experience of European countries. The pattern of population growth began to change in the latter half of nineteenth century, and by the end of the first quarter of the twentieth century these changes were quite dramatic. Birth rates had declined, and outbreaks of epidemic diseases were being controlled. Malthus’s predictions were proved false because both food production and standards of living continued to rise despite the rapid growth of population. "