What is the burden of establishing that a plaintiff has engaged in a prohibited activity?

Under the second prong of our review, "the burden shifts to the plaintiff[s] to demonstrate that each challenged claim based on protected activity is legally sufficient and factually substantiated. The court, without resolving evidentiary conflicts, must determine whether the plaintiff[s'] showing, if accepted by the trier of fact, would be sufficient to sustain a favorable judgment. If not, the claim is stricken." ( Baral v. Schnitt (2016) 1 Cal.5th 376, 396, 205 Cal.Rptr.3d 475, 376 P.3d 604.) "In making this assessment, the court must consider both the legal sufficiency of and evidentiary support for the pleaded claims, and must also examine whether there are any constitutional or nonconstitutional defenses to the pleaded claims and, if so, whether there is evidence to negate any such defenses. [Citation.]" ( McGarry v. University of San Diego (2007) 154 Cal.App.4th 97, 108, 64 Cal.Rptr.3d 467.)