In Order to Measure Staffing Effectiveness, a Company Measures the Yield

In order to measure staffing effectiveness, a company measures the yield ratio of offers to interviews. According to the research, the company yields the following ratios for the following staffing sources: contingency firms (15% first year's salary) 1/10, website (1% G&A costs) 2/12, employee referrals ($0 cost) 3/9, internal recruiters (4% G&A costs) 1/15. Which of the following decisions is a good decision based on the information provided above ?

A) Pursue use of alternate staffing sources
B) Pursue relationships with alternate contingency firms
C) Terminate internal recruiters
D) Promote employee referrals