Task: Question Answering
Input (English): Context: Continuing our look at the presidential candidates , today we look at the hot button issue of the economy . This is a long one , so grab a cold drink and settle in . " John McCain has a comprehensive economic plan that will create millions of good American jobs , ensure our nation 's energy security , get the government 's budget and spending practices in order , and bring relief to American consumers . " " I believe that America 's free market has been the engine of America 's great progress . It 's created a prosperity that is the envy of the world . It 's led to a standard of living unmatched in history . 
Question: What has led to a standard of living unmatched in history ?
Output (English): America 's free market.