Step 1: Analyze the given sentence. "Have this lock broken" is a causative sentence. It means to cause or arrange for someone else to perform an action. It functions as a command.
Step 2: Find the standard passive imperative form. The most common and direct way to express a command in the passive voice is to use the structure "Let + object + be + past participle."
Step 3: Apply this structure. Following the formula, the sentence becomes: "Let this lock be broken." This is the most appropriate passive voice equivalent among the choices.