What is the test for a motion to strike a cause of action arising from constitutionally protected speech or petitioning activity?

"Under California's anti-SLAPP statute, a defendant may bring a special motion to strike a cause of action arising from constitutionally protected speech or petitioning activity. ( 425.16, subd. (b)(1).) Unless the plaintiff establishes a probability of prevailing on the claim, the court must grant the motion and ordinarily must also award the defendant its attorney's fees and costs." (Barry v. State Bar of California (2017) 2 Cal.5th 318, 320.) "The analysis of an anti-SLAPP motion thus involves two steps. 'First, the court decides whether the defendant has made a threshold showing that the challenged cause of action is one "arising from" protected activity. ( 425.16, subd. (b)(1).) If the court finds such a showing has been made, it then must consider whether the plaintiff has demonstrated a probability of prevailing on the claim.' [Citation.] 'Only a cause of action that satisfies both prongs of the anti-SLAPP statute-