Which of the following statements best describes the reason why social networking companies cannot ...

Which of the following statements best describes the reason why social networking companies cannot be sued for defamation for user postings that appear on their sites?
 a. The Communications Decency Act (CDA) uses a vague definition of indecency.
  b. The Communications Decency Act (CDA) is not applicable to social networking sites.
  c. Section 230 of the Communications Decency Act (CDA) is not considered unconstitutional.
  d. Section 230 of the Communications Decency Act (CDA) does not provide immunity to an Internet service provider (ISP).