What is the test for unanimous verdict in a civil case?

"Whenever a defendant is convicted of a crime . . . which is distinguished into degrees, the jury . . . must find the degree of the crime . . . of which he is guilty." ( 1157.) A trial court has a duty to instruct the jury that it must be unanimous as to the degree of the offense. (People v. Avalos (1984) 37 Cal.3d 216, 228.) "When it appears that the defendant has committed a public offense . . . and there is reasonable ground of doubt [as to] which of two or more degrees of the crime . . . he is guilty, he can be convicted of the lowest of such degrees only." ( 1097.)