You have problems with your published canvas app. You want to identify the source expressions or formulas in your app that have errors. 
What four steps should you take to solve your problems?

Answer options:

A.Play published app
B.Open Azure Monitor
C.Turn on Debug published app
D.Run selected app
E.Open Monitor
F.Open Application Insights
G.Select an app

Correct Answers: A, C, E and G 
To troubleshoot an app, you need to use the Power Apps Monitor. A Monitor is a tool that provides a view of the real-time events during your app execution. You can also use the Monitor during your app development. The Monitor helps to debug your app and faster localize code problems. 
When you need to narrow the errors to the source expressions or formulas, you can turn on the canvas app setting “Debug published app” (Number 3) in the app’s Settings (Number 1) under the “Advanced settings” section (Number 2). 

Then you can select your published canvas app in the Power Apps portal and click on the "Monitor" button in the top toolbar or select the three dots for the "More commands" and then the "Monitor" item. You launch your app from the Monitor screen by clicking on the "Play published app" (Number 1). The Power Platform opens a new screen with the app for you to interact. After you finish your operations, you can switch back to the Monitor window and see the operations` timeline and results. When you click on the operation that involves formula, on the Details panel (Number 2), you can review the insights and formula source on the Formula tab (Number 3). 

All other options are incorrect. 
For more information about using the Monitor and other debugging tools, please visit the below URLs: 

https://docs.microsoft.com/en-us/powerapps/maker/monitor-canvasapps
https://powerapps.microsoft.com/en-us/blog/use-monitor-to-debug-your-published-app/