The correct Active/Passive form of the given sentence is:

☀ They will decide to leave the place or not.

Explanation:

The original sentence is already in the active voice: "To leave the place or not will be decided by them." The subject is "them," and the verb is "will be decided."

In the correct option, the sentence remains in the active voice, and the subject "them" performs the action of deciding. The form does not change from active to passive since the original sentence is already in the active voice.

Explanation for other options:

☀ They will have decided to leave the place or not. This option is also in the active voice and correctly represents the decision-making action by "them."

☀ They will have decided to left the place or not. This option is not grammatically correct. The correct form should be "to leave the place," not "to left the place."

☀ They will have decided to leave the place or not. This option is the same as the correct option. It represents the decision-making action in the active voice without changing the meaning of the original sentence.