Your organization has recently focused on expanding its talent pipeline through a new employer branding strategy, aiming to attract a wider range of potential candidates. As part of evaluating the pipeline expansion ROI of this strategy, which of the following metrics would you consider most crucial? a. the increase in overall website traffic to the company's career page, b. the percentage increase in the number of candidates in the talent pipeline who meet the essential qualifications for key roles, c. the diversity of the educational and professional backgrounds of new applicants, or d. the number of shares and likes on employer branding-related social media posts