Final answer:
Emperor Nerva adopted Trajan, an accomplished general and administrator, as his son and heir, marking the commencement of the Five Good Emperors and a prosperous era for the Roman Empire.
Step-by-step explanation:
The question refers to the succession of Roman emperors, specifically regarding whom Nerva adopted as his son and heir. Emperor Nerva chose Trajan, an exceptional general and administrator, as his successor. Nerva's decision was guided by the safety and prosperity of Rome rather than familial ties or nationalism.
This act was a significant event in the Roman Empire's history as it marked the beginning of the rule of the Five Good Emperors, a series of adoptive emperors who were selected for their capabilities rather than their bloodlines. Trajan is celebrated for his military success, particularly against Dacia, and his reign marked a period of prosperity for the Roman Empire. His legacy includes grand architectural projects like the Forum of Trajan.