Universal Container’s Support Manager wants customers to be able to send inquiries to email addresses that can automatically convert customer emails to the case. Which setting would help the Salesforce Admin to do this?

Answer options:

A.Case Escalation Rules
B.Case Auto Response Rules
C.Case Triggers
D.Email-to-Case

Correct Answer: D 
Email to case allows you to get your customers emails into Salesforce cases. So, you let your customers send inquiries to an email address that will be used to convert customer emails to the case. 
Option A is incorrect because case escalation rules determine when a case should be escalated. 
Option B is incorrect because case auto-response rules determine which email templates should be used while sending auto-response messages. 
Option C is incorrect because case triggers define the apex triggers for cases. 
Reference:

https://help.salesforce.com/articleView?id=setting_up_email-to-case.htm&type=5