based on a true story 是电影制作的一种途径,而不是目的.
D选项不定式引导的是目的,显然不对.能在详细些嘛这里based on a true story是作定语修饰the film。还原为：the film was based on a true story。the film was made。组合：the film（which/that was based on a true story） was made.组合后发现主句和从句的谓语部分相同，那么从句的谓语可以省去。变为the film based on a true story was made.再把定语从句的位置调到后面即得到原题。