Select the correct passive form of the given sentence.

I spotted this clock in a junk shop.

This clock was spotted by me in a junk shop.

The correct passive form of the given sentence is This clock was spotted by me in a junk shop.

The other options are incorrect because:

• This clock has been spotted by me in a junk shop uses the present perfect tense, while the original sentence is in the simple past tense.
• A junk shop was spotted in this clock by me is grammatically incorrect. The subject of the sentence is "a junk shop," but the verb "spotted" is in the active voice, which means that the subject is doing the action.
• This clock has spotted me in a junk shop is grammatically incorrect. The subject of the sentence is "this clock," but the verb "spotted" is in the active voice, which means that the subject is doing the action.