What is the threshold burden of demonstrating that a cause of action arises from protected activity?

A defendant meets its threshold burden of demonstrating that a cause of action arises from protected activity by showing that the act or acts underlying the claim fit one or more of the four categories described in section 426.16, subdivision (e). (Navellier v. Sletten (2002) 29 Cal.4th 82, 88, 124 Cal.Rptr.2d 530, 52 P.3d 703.) These categories include any written or oral statement or writing that is made before a legislative, executive, or judicial proceeding, or any other official proceeding authorized by law ( 425.16, subd. (e)(1) ), made in connection with an issue under consideration or review by a legislative, executive, or judicial body, or any other official proceeding authorized by law (id. subd. (e)(2)), or made in a place open to the public or a public forum in connection with an issue of public interest (id. subd. (e)(3)), as well as any other conduct in furtherance of the exercise of the constitutional right of petition or the constitutional right of free speech in connection with a public issue or an issue of public interest (id. subd. (e)(4)).