Cal. Civ. Proc. Code § 1250.350

A defendant may object to the plaintiff’s right to take, by demurrer or answer as provided in Section 430.30, on any ground authorized by Section 1250.360 or Section 1250.370. The demurrer or answer shall state the specific ground upon which the objection is taken and, if the objection is taken by answer, the specific facts upon which the objection is based. An objection may be taken on more than one ground, and the grounds may be inconsistent.