Considering all missing responses from the entire CES-D questionnaire (all 20 CES-D items), what is the average percentage of missing data overall? Question 17 options: 17.3% of missingness in CES-D questionnaire 3.2% of missingness in CES-D questionnaire 3.8% of missingness in CES-D questionnaire 1.8% of missingness in CES-D questionnaire