Answer:
<h2>Legalized Christianity.</h2>
Explanation:
Trajan was the greatest emperor in the History of Rome and ruled fro 19 years from 98 AD to 117 AD. He was thirteenth Roman Emperor.He added many lands to the Roman empire and the empire reached its largest expanse in history. His rule was period of prosperity for Rome. He was appointed Emperor Nerva's heir in 98 AD , at that time he was serving as the governor of Upper Germany. After becoming the emperor he first annexed the kingdom of Dacia(Romania) and later the kingdom of Parthia. He also won Armenia and Mesopotamia.
Public works were at its peak during his rule. His public works included aqueducts, baths, canals, public buildings and roads.The bridge constructed by him over river Danube was the longest arch bridge in the world for 1000 years.He helped the poor through welfare programs called Alimenta.
Tarjan didn't legalised Christianity, it was emperor Constantine who issued edict of Milan in 313 AD and accepted Christianity, it became the state religion ten year later.
