what general political Trend coincided with the significant increase in private and corporate spending

What general political trend coincided with a significant increase in private and corporate spending in political campaigns at the turn of the 21st-century

A withdrawal of people from the public sphere

Explanation:

At the beginning of 21-century or the new millennium, various research have shown that, coupled with the advent of the internet fair loss of interest in active politics by the general populace, a larger percentage of the general public has withdraw from the public space in terms of politics. This has led to substantial increase in private and corporate spending in political campaigns at the turn of the 21st-century.

Hence, the right answer is: A withdrawal of people from the public sphere