Todd, a sales representative for a textbook publisher, knows the name and direct line of each client's administrative assistant. Which type of software system most likely helps Todd keep track of this information?

A) GIS
B) POP
C) Inventory management
D) CRM
E) Calendar management

CRM (Customer Relationship Management) software is designed to help businesses manage and analyze customer interactions and data throughout the customer lifecycle. It helps in organizing information such as clients' contact details, preferences, and history with the company, which is exactly what Todd is doing by keeping track of the names and direct lines of each client's administrative assistant.