Final answer:
The best place to store student grade data is a student information system because it offers enhanced security and ease of access for managing educational records.
Step-by-step explanation:
The best place to store student grade data is C. A student information system. This system is typically an online platform specially designed for educational institutions to manage and store student data securely. Unlike the options presented in A and B, which rely on personal hard drives, a student information system generally includes enhanced security features to protect sensitive information and allow for easy access and backup by authorized personnel. In contrast, option D, although secure, does not provide the ease of access and management that electronic systems offer.