Very confused question, because has two correct answers. Post feed item or Update a record are correct answers, the answer depends which feature will be used to do this.
The question has 3 correct answers, because Fore.com IDE can also download debug logs in the new versions.
A Workflow never can update child records, this is a capability of process builder, then the correct Answers are:Create activities at mutiple intervals Send an outbound message without Apex code.
If create a master-detail relationship in the Job Posting, just one Application can be related to Job Posting. If others candidates desires aplly yours Application to same Job Posting, they are won't be able.
Por isso a resposta correta é:Create a master-detail relationship in the Application custom object to the Job Postings custom object.
This answer is definitely wrong because the child cases created by this trigger will fire again the same trigger that will create new child cases, which in turn will trigger the trigger again, thus generating the looping.
So the correct answer would be:The trigger enters an infinite loop and eventually fails.