Final answer:
Among the options provided, Judaism (D) is the religion where missionary work was never a significant practice, as it traditionally does not actively seek converts.
Step-by-step explanation:
The question 'Missionary work was never important to which religion? A) Christianity B) Islam C) Buddhism D) Judaism' pertains to the role of missionary work in different religious traditions. Answering this requires an understanding of the historical and religious practices of proselytization associated with these faiths.
Missionary work has been a significant aspect of Christianity and Islam, with both religions actively seeking to convert non-believers and spread their faiths. Buddhism also has a history of proselytization, though it has varied in intensity and method across different Buddhist traditions and time periods. However, when it comes to Judaism, missionary work has traditionally been not significant. Judaism does not actively seek converts, and the process of conversion to Judaism is typically reserved for those who independently seek to join the faith, rather than being actively sought out through mission work.