I need help with this question.

Can someone tell me if this is perpendicular? !

Use sigma notation to represent the following series for 9 terms.

Kilgore trout creates a new scale to diagnose depression. however, his scale only assesses one symptom of depression while ignoring others. which of the following is his new scale most likely lacking? a) test-retest reliability b) discriminant validity c) criterion validity d) alternate-forms reliability e) content validity f) none of the above