What type of analysis seeks to answer the question, "What has happened?"

Descriptive analytics is focused on understanding and interpreting historical data to answer questions about past events or trends. It seeks to summarize past performance and understand what has occurred over a given timeframe by using techniques such as data aggregation, reporting, and visualization. This type of analysis often employs statistical methods to create reports that inform stakeholders of previous activities, patterns, or results.

In contrast, predictive analytics forecasts future outcomes based on historical data, while prescriptive analytics recommends actions based on various scenarios. Causal analysis investigates the cause-and-effect relationships between variables, rather than simply describing what has happened. Therefore, descriptive analytics is the correct choice for answering the question, "What has happened?" as it explicitly focuses on summarizing and interpreting preceding events.