GWD15里面的几题语法题,找不到讨论,请大NN指导

Q20:

In January 1994 an oil barge ran aground off the coast of San Juan, Puerto Rico, leaking its cargo of 750,000 gallons into the ocean, while causing the pollution of the city’s beaches.

1. leaking its cargo of 750,000 gallons into the ocean, while causing the pollution of

2. with its cargo of 750,000 gallons leaking into the ocean, and it polluted

3. and its cargo of 750,000 gallons leaked into the ocean, polluting

4. while it leaked its cargo of 750,000 gallons into the ocean and caused the pollution of

5. so that its cargo of 750,000 gallons leaked into the ocean, and they were polluting

   Answer: C

BDE中的and，找前后并列，发现都有逻辑关系错误，不是运油的船本身或者gallons造成污染，而是油船ran off and leaked整件事情造成了污染，所以选择c，前后两个动作并列，polluting修饰整体。

a 表达不出这层意思，并且罗嗦.

请指教