Which of the following is true regarding the grand jury system? a. under the u. s. constitution, a grand jury is required in state court felony casesb. under the u. s. constitution, a grand jury is required in federal felony casesc. the right to a grand jury may not be waived by a defendantd. under the u. s. constitution, a grand jury is required in state court felony cases and in federal felony cases and the right to a grand jury may not be waived by a defendante. under the u. s. constitution, a grand jury is required in both state and federal felony cases, but a defendant may waive the right to review by a grand jury