Step 1: Understanding the Concept:
- A Social Problem is a social condition that a significant number of people in a society consider to be undesirable and in need of collective action to remedy.
- A Social Process is a general pattern of social change or interaction.
Step 2: Detailed Explanation:
- (A) Child labour, (B) Corruption, and (C) Trafficking are all conditions that cause significant harm and are widely regarded by society as serious problems that need to be solved.
- (D) Modernization is a broad, large-scale process of social change involving industrialization, urbanization, and secularization. It is a neutral, analytical concept used to describe a type of societal transformation. While modernization can \textit{lead to} social problems (such as anomie, inequality, or environmental degradation), the process itself is not defined as a social problem.
Step 3: Final Answer:
Modernization is a social process, not a social problem.