The Biggest Difference(s)between a Private Employment Agency and a Professional

The biggest difference(s) between a private employment agency and a professional search firm is

A) that professional search firms tend to be more specialized
B) that search firms tend to seek out non-specific unskilled recruits
C) that professional search firms do not charge the employer/client a fee for service
D) that private employment agencies are federally licensed
E) professional search firms do not recruit from among the employees of other firms