Coagulation, the removal of iron salts from drinking water, as a method of the extraction of toxic metal ions, it was well established as early as the 17th century, but until about 50 years ago scientists did not realize that activated carbon took an active part in the process.
A – as a method of the extraction of toxic metal ions, it was well established.
B – as a method of the extraction of toxic metal ions well established
C – was a well-established method of toxic metal ions extraction
D – was a well-established method of extracting toxic metal ions that was
E – had been a method of toxic metal ions extraction, well established
Right Answer: C
|Underlined Verb “was||Pronoun|
|Past perfect tense ‘had been’ in an option||Tense|
Since we have identified the sentence to have an error that is based on Sentence Fragments and Tenses, we will try and eliminate those options first.
A – Eliminated due to incorrect usage of the pronoun ‘it’. The sentence is fragmented.
B – Eliminated as the sentence is fragmented.
C – This is the right answer and there is no grammatical error here.
D – Eliminated due to the incorrect usage of ‘that’ as it refers to toxic metal ions.
E – Eliminated due to the incorrect usage of past perfect tense ‘had been’.