The clue here is viewed by itself and the use of but indicates that the next word should be opposite of itself something like the when viewed together.

A. Isolation- something similiar to itself- Out
B. Concert-
C. Intransigence-this means not changing one’s view-Out
D. Conjunction
E. Obsequy- means funeral rites-Out
F. Insularity- means isolation

Here, Isolation & insularity have similar meaning, and obsequy & intransigence do not have similar meaning. Concert & conjunction survive. Even though i was not sure whether conjunction and concert have similar meaning but these are the only viable options.

Hope this helps!

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