What metric-dimension combination is not valid?

What report identifies browsers that may have had problems with a website?

The Source/Medium report The New vs Returning report The Browser & OS report The Active Users report Download Google Analytics Individual Certification Exam Answers (PDF)

What feature is required to collect the number of comments users posted to a web page?

Custom Metric Custom Channel Groupings Custom Dimension Calculated Metric Download Google Analytics Individual Certification Exam Answers (PDF)

Once filters have been applied, what is the option to recover filtered data?

Data may be recovered within 30 days Filtered data is not recoverable Data may be recovered within 10 days Data may be recovered within 5 days Download Google Analytics Individual Certification Exam Answers (PDF)