They're biggest mistake was going through ice but they ended up having another problem which was how cold it was but they over came the cold by wearing alot of layers of clothes they also took all the wet clothes off very fast and had hot drinks often the last problem they had was drifting ice pans which could collide causing walls of ice to ride out of nowhere or to break apart throwing them into the freezing Waters far away.
Slave labor was unpaid and made up the majority of the workforce.
Option A consists of two independent clauses, therefore there's a coordinating conjunction in between them to help the sentence flow.
It is not D or B so it must be a or c. I'm guessing it would be A.
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