Final answer:
A PivotTable is the best tool in Excel for deep diving into data, enabling the reorganization and summarization of complex data to discern patterns and insights(option a).
Step-by-step explanation:
To aid with deep diving into data within Excel, a PivotTable is an excellent tool(option a).
A PivotTable allows you to reorganize and summarize complex data, making it easier to find patterns and gain insights. While the other options provided, such as VLOOKUP, Macros, and Sparklines, serve various purposes—VLOOKUP for searching specific data within a column, Macros for automating repetitive tasks, and Sparklines for creating small, simple charts within a cell—a PivotTable is the best choice for comprehensive data analysis.