Use the verbs in brackets in the correct tense to fill in the gaps. Choose the correct option.

We ___________________ \(explore\) a haunted castle for about half an hour when it _________________ \(turn out\) that we ________________ \(leave\) our ghost hunting equipment at home.

• had been exploring, turned out, had left
• had explored, turned out, left
• were exploring, turned out, had left
• explored, turned out, left