What is the meaning of section 190.5(b) of the California Penal Code when it refers to life without parole?

read the text to mean that a court may select one of the two penalties in the exercise of its discretion, with no presumption in favor of one or the other. The latter reading accords with common usage. For example, if a teacher informed her students that 'you must take a final exam or, at your discretion, write a term paper,' it would be reasonable for the students to believe they were equally free to pursue either option. The text of section 190.5[, subdivision ](b) does not clearly indicate whether the statute was intended to make life without parole the presumptive sentence." (People v. Gutierrez, supra, 58 Cal.4th at p. 1371.)