The correct answer is public issue. According to Mills, a public issue is a problem that affects a large number of people and requires collective action to solve. A personal trouble, on the other hand, is a problem that affects an individual or a small group and can be solved by personal effort. Mills argues that divorce should be analyzed as a public issue, not as a personal trouble, because it reflects the structural changes and conflicts in the institution of marriage and the family. He suggests that divorce is not merely caused by the personal choices or failures of the spouses, but by the social and historical forces that shape their lives. For example, he points out that divorce rates are higher among certain groups, such as urban dwellers, industrial workers, and women with higher education. He also notes that divorce rates vary across different periods of time, such as during wars, depressions, or social movements. These patterns indicate that divorce is influenced by factors beyond the control of the individuals involved, such as economic conditions, cultural norms, legal regulations, and political events. Therefore, Mills claims that to understand the causes and consequences of divorce, one must use the sociological imagination to connect the personal experiences of the divorcing couples to the wider society.