Any aggregated field in a SELECT list that does not have an alias automatically gets an implied alias with a format expri, where i denotes the order of the aggregated fields with no explicit aliases.

https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/langCon_apex_SOQL_agg_fns.htm

Correct answer: A,B

Any aggregated field in a SELECT list that does not have an alias automatically gets an implied alias with a format expri, where i denotes the order of the aggregated fields with no explicit aliases.

https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/langCon_apex_SOQL_agg_fns.htm

In the case of the answers posted by Phat, Example 1 and Example 2 both work. You can test it yourself in Execute Anonymous. ar.get.AVG() gets an error because there is no variable called .get. Similar issue for Example 4.

The examples are:

Example 1:
AggregateResult[] groupedResults = [SELECT CampaignId, AVG(Amount) FROM Opportunity GROUP BY CampaignId]; for (AggregateResult ar : groupedResults) {
System.debug(‘Campaign ID’ + ar.get(‘CampaignId’));
System.debug(‘Average amount’ + ar.get(‘expr0’)); }
Example 2:
AggregateResult[] groupedResults = [SELECT CampaignId, AVG(Amount) theAverage FROM Opportunity GROUP BY CampaignId]; for (AggregateResult ar : groupedResults) {
System.debug(‘Campaign ID’ + ar.get(‘CampaignId’));
System.debug(‘Average amount’ + ar.get(‘theAverage’)); }
Example 3:
AggregateResult[] groupedResults = [SELECT CampaignId, AVG(Amount) FROM Opportunity GROUP BY CampaignId]; for (AggregateResult ar : groupedResults) {
System.debug(‘Campaign ID’ + ar.get(‘CampaignId’));
System.debug(‘Average amount’ + ar.get.AVG()); }
Example 4:
AggregateResult[] groupedResults = [SELECT CampaignId, AVG(Amount) theAverage FROM Opportunity GROUP BY CampaignId]; for (AggregateResult ar : groupedResults) {
System.debug(‘Campaign ID’ + ar.get(‘CampaignId’));
System.debug (‘Average amount’ + ar.theAverage); }...

The examples are not visible