Which of the following scenarios illustrates the concept of voluntary jurisdiction? (More than one answer might be literally true. Choose the best one.)

a. An out-of-state defendant who signs a contract containing a forum selection clause in which the parties agree to litigate any disputes in the designated forum state.

b. An out-of-state defendant who knowingly makes a defamatory statement with the purpose of causing injury to the defamed person in that person’s forum state.

c. An out-of-state defendant who owns an interactive website accessible to users in the plaintiff’s forum state.

d. An out-of-state defendant who inherits property under a contested will.

e. An out-of-state defendant who travels to the plaintiff’s forum state.