Final answer:
Ezra led the religious reform between 450 and 400 BCE, centered on the renewal of the covenant and strict adherence to the Torah, reinforcing Jewish identity post-Babylonian captivity.
Step-by-step explanation:
Between 450 and 400 BCE, the person who led the people in religious reform centered on renewal of the covenant and obedience to Torah was Ezra. After the return from the Babylonian captivity, Ezra was instrumental in the re-establishment of the Torah-centered Jewish community. His contributions included the compilation of the Torah into a single text and promoting strict adherence to its laws among the Jewish exiles, which solidified the identity and religious practices of the Jewish people during that time.