Þ C. THE DATASET IS SEGMENTED BY THE SALARY COLUMN. THIS CREATES TW...

6. þ C. The dataset is segmented by the SALARY column. This creates two groups: one with SALARY values of 100 and the other with a null SALARY value. The average length of SALARY value 100 is 3 for the rows in the first group. The NULL salary value is first converted into the number 0 by the NVL function, and the average length of SALARY is 1. The SUM function operates across the two groups adding the values 3 and 1, returning 4.ý A, B, and D. A seems plausible, since group functions may not be nested more than two levels deep. Although there are four functions, only two are group functions, while the others are single-row functions evaluated before the group functions. B would be returned if the expression SUM(AVG(LENGTH(SALARY))) were selected.