Answer: A, B
A. The default modifier for a class is private.
The top-level of the type must set Public or Global for the modifier. So an only inner class can ignore to set, which default to private.
C is incorrect. Because a class only can have 1 levels of inner class.
D is incorrect. Interface is a top level of type, that must ...
Trigger is fired twice: 1st: 15:19:41.0 (5713537)|USER_DEBUG||DEBUG| old test_number_2__c: 1 15:19:41.0 (7522682)|USER_DEBUG||DEBUG| new test_number_2__c: 10 2nd: 15:19:41.71 (73753198)|USER_DEBUG||DEBUG| old test_number_2__c: 1 115:19:41.71 (75599696)|USER_DEBUG||DEBUG| new test_number_2__c: 11
A is incorrect because the field won't add to layout automatically.
D is incorrect because fields won't be hide
The Recursive fails when it exceeds 16 times that is limitation of trigger rescursive invocation.
Total stack depth is 16 for any Apex invocation that recursively fires triggers due to insert, update, or delete ...
Answer: 1In each specified relationship, only one level of parent-to-child relationship can be specified in a query. For example, if the FROM clause specifies Account, the SELECT clause can specify only the Contact or other objects at that level. It could not specify a child object of Contact. Please reference: ...