Select the most appropriate option to complete the given sentence.

They were not able to get the item from the store because it was _______.

out of stock

The most appropriate option to complete the given sentence is out of stock.

This is because the sentence is about someone who was unable to get an item from a store because it was not available. The phrase "out of stock" means that the item is not currently available for purchase.

The other options are incorrect.

• In fashion means that the item is popular and stylish. It does not make sense to say that the item was out of stock because it was in fashion.
• In vain means that an effort was unsuccessful. It does not make sense to say that the item was out of stock because the effort to get it was unsuccessful.
• On leave means that the item is not available because the person who is responsible for it is not working. It does not make sense to say that the item was out of stock because the person who is responsible for it is not working.