Muckraking occurs when newspapers
investigate problems in government and business
investigate actions of celebrities
print sensational news on the front page to sell papers
print more editorials and opinion pieces to sell papers

Muckraking occurs when newspapers investigate problems in government and business.

Explanation:

Muckraker is the name by which were known the journalists who, at the beginning of the 20th century, dedicated themselves to publicly denouncing political corruption, labor exploitation and a series of abuses, immoralities and dirty rags of characters and institutions of the time.

It is a journalism of opposition to power, an activist and underground movement that supposes an attempt, strictly professional, to overcome the information saturation, characterized by standardization and the accumulation of data and make a type of journalism aimed at provoking a response.