What is an accurate constructor for a custom controller named "MyController"?

What is an accurate constructor for a custom controller named "MyController"?
A . public MyController () { account = new Account () ; }
B . public MyController (sObject obj) { account = (Account) obj; }
C . public MyController (List objects) { accounts = (List ) objects; }
D . public MyController (ApexPages.StandardController stdController) { account = (Account) stdController.getRecord(); }

View Answer

Answer: A