Fill in the blank given below using the correct idiom.  John thought his missing keys were stolen by his roommate, but he was ______________ because he later found them in his own backpack.

The idiom "barking up the wrong tree" means pursuing a mistaken or misguided approach. (A) standing in good stead: To be beneficial or advantageous in the future. (B) killing two birds with one stone: Achieve two objectives or complete two tasks with a single action. (C) sinking their teeth into: To fully engage with or become deeply involved in something. (D) barking up the wrong tree: Pursuing a mistaken or misguided approach. (E) cutting corners: Completing a task quickly or without following proper procedures.