Which of the following statements about public police officers who work for private security firms ...

Which of the following statements about public police officers who work for private security firms is TRUE?
 
  a. Congress passed a law making it illegal for public police officers to work for private firms.
  b. It is legal for public police officers to work for private firms, but they never retain their full powers and status as police personnel.
  c. It is almost always legal for public police officers to work for private firms, and they may retain their powers and status as police personnel.
  d. Very few police officers work for private firms.
  e. There is no conflict of interest if a public police officer works for a private firm.