How did the Royal Road benefit the Persians? A. It prevented invaders from entering the Persian Empire.
B. It encouraged the building of Persian naval vessels.
C. It established communication throughout the Persian Empire.
D. It helped the Persians reach Rome and then conquer it.

It established communication throughout the Persian Empire

Explanation:

The Royal Road was an antiquated interstate rearranged and reconstructed by the Persian lord Darius the Great (Darius I) of the first (Achaemenid) Persian Empire in the fifth century BCE. Darius fabricated the street to encourage fast correspondence all through his enormous domain from Susa to Sardis.

Royal road established communication throughout the Persian Empire.

im not sure on this one