Sentence Correction

Leaching, the recovery of copper from the drainage water of mines, as a method of the extraction of minerals, it was well established as early as the eighteen century, but until about 25 years ago miners did not realize that bacteria take an active part in the process.

A) as a method of the extraction of minerals, it was well established

B) as a method of the extraction of minerals well established

C) was a well-established method of mineral extraction

D) was a well-established method of extracting mineral that was

E) had been a method of mineral extraction, well established

OAC

Please explain.

A sentence must make perfect sense if non-essential modifiers are removed.

Here, 'the recovery of copper from the drainage water of mines' is a non-essential modifier (a modifier separated by commas).

The sentence now is -
Leeching [as a method of the extraction of minerals], it was well established ...
Note that the part enclosed in the square brackets is a modifier to the noun - Leeching.
The sentence essentially says this -
Leeching, it was well established ... - this sentence is incorrect. (this sentence is similar to this -John, he went to the movies).

A - incorrect.

B - essentially the sentence is this -
Leeching [as a method of the extraction ....], but + Clause.
Note that 'but' requires parallel structure (just like 'and').

Leeching + Modifier cannot be parallel to a Clause - hence, B is incorrect.

C - correct answer. Note that we are referring to a specific point in the past - 18th century.
Hence, past tense 'was' is used.

D - "method of extracting mineral that was as early as the 18th century".
this implies "method that was as early as the 18th century" - absurd.

E - usage of past perfect 'had been' is incorrect.

B - essentially the sentence is this -
Leeching [as a method of the extraction ....], but + Clause.
Note that 'but' requires parallel structure (just like 'and').

Leeching + Modifier cannot be parallel to a Clause - hence, B is incorrect.

Hi Crackverbal ,

Thanks for your explanation.

All clear. Can you please explain more option B?

Many thanks in advance.

Kavin

Whatever follows the 'but' is a clause. 'but' requires parallelism

look here -
but [until about 25 years ago] miners did not realize that bacteria take an active part in the process.

the main clause is this -
'miners did not realize that bacteria take an active part in the process'.

this - 'until about 25 years ago' is a modifier.

1st part of the sentence -
Leaching, [the recovery of copper from the drainage water of mines], as a method of the extraction of minerals well established as early as the eighteen century

I can remove the phrase in square brackets as it is a non-essential modifier.

I am left with this -
Leaching as a method of the extraction of minerals well established as early as the eighteenth century.

this is not a sentence/clause. There is no verb in the clause.
'well established' is a modifier, not a verb. (Because, this is not a sentence - 'Leeching [as a method of extraction] well established as early as 18th century'. Delete the phrase in the square brackets and you will see that it is not a sentence.)

hello
thank you for you help .
can you please explain about D?
I understand that seems method was as early as 18 century but i think method refers to leaching and this is correct....

could you correct me?