A sentence is given with three words marked as (A), (B), and (C). These words may or may not be placed in their places. Four options with different arrangements of these words are given. Mark the option with the correct arrangement as the answer. If there is no change required, mark 'No rearrangement required' as your answer.

While little was known(A) about the virus then, civic authorities (B) across the country were faced with the mammoth task of ensuring (C) social distancing.