Convert the sentence provided below from its passive voice structure to an active voice structure:

The coastal highway is reported to have been evacuated due to storm warnings.

The correct option is: Authorities report that they have evacuated the coastal highway due to storm warnings.

To convert a sentence from passive voice to active voice, follow these step-by-step grammatical steps:

Step 1: Analyze the passive sentence structure
The original sentence is: "The coastal highway is reported to have been evacuated due to storm warnings."
It contains two passive verbal components:
1. Primary reporting verb: "is reported" (Present simple passive)
2. Dependent infinitive phrase: "to have been evacuated" (Present perfect passive infinitive)

Step 2: Identify or supply the active subject (agent)
The original passive sentence omits the agent performing the action. To make the sentence active, we must supply a logical subject who performs both reporting and evacuating, such as "Authorities".

Step 3: Convert the primary reporting verb
Change the passive construction "is reported" into the active form in the present tense:
⇒ Authorities report that...

Step 4: Convert the dependent passive infinitive to active tense
The perfect passive infinitive "to have been evacuated" shows that the action was completed. Changing this to active voice with the pronoun "they" yields the present perfect active verb "have evacuated":
⇒ ...they have evacuated the coastal highway...

Step 5: Assemble the complete active sentence
Combine the active clauses with the original prepositional phrase indicating cause ("due to storm warnings"):
⇒ Authorities report that they have evacuated the coastal highway due to storm warnings.

Step 6: Review the options
- Storm warnings reportedly evacuated the coastal highway: Incorrect, as storm warnings cannot physically evacuate a highway.
- Rescuers reportedly evacuated the coastal highway because of storm warnings: Incorrect, because it drops the main reporting clause structure.
- Authorities report that they have evacuated the coastal highway due to storm warnings: Correct, as it properly converts both passive verb forms into active forms with a logical subject.
- It is reported that the emergency teams evacuated the coastal highway due to storm warnings: Incorrect, because "It is reported" remains an impersonal passive phrase.