What does functional testing typically involve?

Functional testing primarily focuses on verifying that software applications perform according to their specified requirements and functions as expected. This involves validating the features and behaviors of the application under various scenarios.

The most relevant aspect of functional testing among the provided options is the mobilization of personnel at various geographic sites. This reflects the collaborative effort often required when testing software, especially in distributed environments or when the application is designed to work across multiple locations. Testing teams may need to coordinate across different sites to ensure the application functions correctly under varied conditions and user interactions.

The other options pertain to different activities that do not directly align with the core principles of functional testing. Analysis of transaction logs is more aligned with auditing and performance analysis, coordination of communication strategies typically falls under project management or change management, and the use of check digits for validation relates to data integrity rather than functional testing processes. Hence, the correct response is rooted in the collaborative operational aspects of functional testing, aligning it closer to effective validation of software functionality across multiple user environments.