George is a recruiter at a growing technology startup. Despite a surge in the volume of job applications, the 'time to hire' has been trending upwards, suggesting inefficiencies in the recruitment process. George decides to perform a data drill-down analysis to uncover more granular insights that could help streamline the process. Which area should George specifically drill down into to understand potential inefficiencies and improve the quality of the recruitment pipeline? a. the geographical locations of applicants, b. the demographic factors of applicants, c. the sources of applications, or d. the yield ratio for each stage