Final answer:
The Hebrew word referring to the collection of Jewish traditions compiled in the early 3rd century AD, which comes from a root meaning "to repeat," is the Mishnah (b).
Step-by-step explanation:
The Hebrew word, derived from a root meaning "to repeat," that refers to the collection of beliefs and regulations of the Jews compiled around the early 3rd century AD is b) Mishnah.
The Mishnah is a significant part of the Jewish oral traditions and is regarded as the first major written redaction of the Jewish oral traditions known as the Oral Torah. It reflects the discussions and beliefs of Jews from as early as 50 BC. The Mishnah is part of the larger text known as the Talmud, but the Talmud also includes the Gemara, a later commentary on the Mishnah. By contrast, the Midrash contains homiletic teachings that explore the connections between biblical texts, and Halakah refers to the collective body of Jewish religious laws derived from the written and Oral Torah.
Knowledge of the Mishnah and the Talmud represents an essential aspect of understanding Jewish law, ethics, and history. The ability to transport their religious culture, as encapsulated in the Torah and its oral interpretations including the Mishnah, was crucial for the Jews in maintaining their distinct identity, especially after being scattered by the Romans across various regions.