The detail that supports the answer in part A shows that opponents launched the longest obstruction in American history, which lasted 57 days and brought the senate to a vital standstill, as shown in option D.
We can reach this answer because:
We can say that this is the correct answer because Part A shows that the passage of the Civil Rights Act had many difficulties to be accomplished. This can be proven by the fact that opponents of this law were dedicated to making long papers and arguments, capable of lasting 57 days and causing a virtual standstill.
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