"The company is believed to have acquired the land illegally through forged documents."
(Note: Among the options provided in the prompt, "The company is believed to have acquired the land illegally." is the closest and most accurate option, though it omits the prepositional phrase "through forged documents" for brevity).
Detailed Explanation
To convert a complex sentence from passive to active voice, we need to analyze its components:
Identify the Subject and Object of the main action:
Passive Action: "...to have been acquired illegally by the company..."
Here, "the company" is the agent doing the acquiring (the logical subject), and "the land" is the entity being acquired (the logical object).
Transforming the Infinitive Phrase:
The passive infinitive "to have been acquired" (Perfect Passive Infinitive) must be changed into the active infinitive "to have acquired" (Perfect Active Infinitive).
Therefore, "the land... to have been acquired... by the company" becomes "the company... to have acquired the land".
Handling the Stative Verb ("is believed"):
The phrase "The land is believed..." uses an impersonal passive construction.
When shifting the focus to the company performing the primary action, the active framework smoothly transitions to: "The company is believed to have..." (This retains the original meaning that the belief is held by people/general public without changing the tense).