你好。答案是causing. 是分词结构做伴随状态,与rained同时发生。
==It rained heavily in the south, which caused serious flooding in several provinces.(定语从句)
==It rained heavily in the south and caused serious flooding in several provinces. (并列句)
C 是causing吧?
having caused 是doing的完成时结构, 表示发生在谓语动词前,=after doing
这里, 导致严重的洪水,明显发生在谓语动词, rained之后了,当然不能用having caused
C caused