Underlined portion: which I previously leaved in the den.
Answer:
which I left in the den.
Step-by-step explanation:
The underlined portion is wrong mainly because the verb “leaved” is bad conjugated. This verb is an irregular one and its form in the past tense is “left.” The best revision is “which I left in the den” because it is well written, concise and matches the informal tone of the previous phrase. The other options, on the other hand, are wordy or too formal.