Option 1 -> "on the fence" means being undecided or uncertain about something, which doesn't fit the context of getting a coveted job.
Option 2 -> "under the weather" means feeling ill or unwell, which is unrelated to the job context.
Option 3 -> "over the moon" means extremely happy or delighted, which perfectly describes someone's emotion about getting a highly desired job.
Option 4 -> "barking up the wrong tree" means pursuing a wrong or misguided course of action, which doesn't fit here.
Hence, Option 3: over the moon -> This idiom correctly expresses Ravi's extreme happiness and excitement about securing the much coveted job he desired -> correct