Final answer:
The documentation tool that Nishant Kumar should employ is a document flowchart. option b.
Step-by-step explanation:
The documentation tool that Nishant Kumar should employ for documenting the existing accounting information system in preparation for making recommendations for improvements to internal controls is a document flowchart.
A document flowchart is a graphical representation that illustrates the flow of documents in a system, including the sources and destinations of those documents. It provides a visual overview of the paper records and how they move through the accounting information system. This tool helps in understanding the current process and identifying potential gaps or areas for improvement in internal controls.