When presented with only circumstantial evidence, a juror tends to decide a case according to his or her gut instinct,
which are not formally sanctioned or prohibited means of reaching a verdict.
the underline portion indicates that this clause is a relative clause that tries to modify the noun immediately preceding it. In this case, the noun is the
'gut instinct', which is singular in nature. Hence, it
must be matched by a singular verb.(A)
which are not formally - here, we have a singular noun (in the preceding clause) but a plural verb (are). There's a subject-verb agreement problem here. Hence,
eliminate (A)(B)
which are not a formally - here, the same error exists as in (A). So,
eliminate (B)
(C)
which is not a formally - this clause tries to modify the noun 'gut instinct'. So, to understand this option better, let us isolate the relation between this noun and the succeeding clause.
Part 1. Gut instinct is not a formally sanctioned mean
Part 2. Gut instinct is not a formally prohibited means.
As you can see, the above structure makes perfect sense.
Hence,
(C) is the right answer. (D)
which is formally not a - let's analyze this in the same way that we did for (C)
Part 1. Gut instinct is formally not a sanctioned mean
and
Part 2. Gut instinct is formally not a prohibited means.
We can therefore make an inference that this structure (as used in (D) ) changes the intended meaning. besides, I dont think that Part 1 (in option D) makes sense.
Hence,
eliminate (D)(E)
which is not formally-
Let's perform the same 'part analysis' as is done in (C) and (D)
Part1. Gut instinct is not formally sanctioned mean
Part 2. Gut instinct is not formally prohibited mean
In both these parts, an article ('a') is missing. Moreover, this further defines what the items (or terms) that a 'gut instinct' does not have; this structure does not tell us anything about whether the usage of 'gut instinct' (by a juror in deciding a case) is prohibited or sanctioned. there's a lot of ambiguity here. Hence,
eliminate (E)