Final answer:
The adverb clause "when the shop is closed" is correctly punctuated as "When the shop is closed, we can go out to eat."
Step-by-step explanation:
The correct sentence that punctuates the adverb clause "when the shop is closed" is option C: When the shop is closed, we can go out to eat. In this sentence, a comma is used to separate the adverb clause from the main clause, providing clarity and following proper punctuation rules.
Learn more about Punctuation in English sentences