What is the Persian royal road?

The Royal Road was an ancient highway reorganized and rebuilt by the Persian king Darius the Great (Darius I) of the first (Achaemenid) Persian Empire in the 5th century BCE. Darius built the road to facilitate rapid communication throughout his very large empire from Susa to Sardis.

it was made because he wanted to try to make people convert as well people who would have read or studied this item at the time it was created were probably people who wanted to change religions who thought conversion was a good idea.

a is correct

hope this let me know if it is right