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