Question

Select the correct and entire subordinate clause of the sentence.

A huge quantity of toxic materials, which had been dumped into the city water system, contaminated a major waste treatment plant.

The subordinate clause is _____.

Answer 1

The correct and entire subordinate clause of this sentence is which had been dumped into the city water system.
A subordinate clause is dependent, meaning that it cannot stand on its own - it can only exist in an independent clause.

Answer 2

Answer:

The answer to your question would be that the entire subordinate clause of the sentence is "which had been dumped into the city water system".

Explanation:

The sentence above contains a nonessential relative clause.  This subordinate clause modifies the noun head materials but it is nonessential. This is so because the information it provides is not necessary to complete the meaning of the sentence. Consequently, if it was dropped, it would not altered the meaning (see A). This is also why the clause is separated from the rest of the sentence with commas.

A) A huge quantity of toxic materials contaminated a major waste treatment plant