The usage of 'and' just before the last clause of the sentence (right after the underlined portion) here indicates parallelism. So, the concept of parallelism is something that you need to pay attention to.
The process of digital remastering is the method by which analog sound recordings are converted to digital files, edited to remove undesirable audio artifacts introduced during analog recording, and filtered to enhance the overall quality of the sound.
(A)
The process of digital remastering is the method by which analog sound recordings are converted to digital files - Based on the initial reading, this looks good. (A) proceeds by saying that the process of digital remastering..... . Okay, so we know that digital mastering is some sort of process that does something (keep this idea in mind).
Let's shortlist (A).(B)
The process of digital remastering is the way that analog sound recordings are converted to digital files - the process... is the way that... are converted??? This makes no logical sense.
Eliminate (B)(C)
Digital remastering is the process by which analog sound recordings are converted to digital files - very similar to (A). For the same reasons indicated in the explanation of (A),
let's shortlist (C) as well. (D)
Digital remastering occurs when analog sound recordings are converted to digital files - Okay. wait a second. what (D) does is that it reduces the significance of digital remastering to some sort of process that occurs as a result of (what ever that follows this phrase). From what we know after reading (A), we know that digital remastering is some sort of process, not a result of something. This changes the intended meaning of the sentence. Hence,
eliminate (D).
(E)
Digital remastering, the process by which analog sound recordings are converted to digital files - Now, (E) introduces the following structure: [Noun] (Digital remastering), [noun modifier], [noun modifier], and [noun modifier]. But what exactly is happening here? where is the verb? what aspect of the noun (the subject digital remastering) are we trying to highlight using this structure? (E) leaves a lot of room for confusion to set it and in itself is incomplete. hence,
(E) is eliminated. Now, we are left with answer choices (A) and (C)
Let's compare them here:
(A)
The process of digital remastering is the method by which analog sound recordings are converted to digital files (C)
Digital remastering is the process by which analog sound recordings are converted to digital filesNotice that meaning wise, both (A) and (C) are quite similar to each other. But since (C) is much less wordier and still conveys the intended meaning of the sentence in a much concise manner, (C) will be considered the best option here. Hence,
(C) is the right answer.