Some twentieth–century art is great art. All great art involves original ideas, and any art that is not influential ...

Irina on October 21, 2019

@acarerra,

Let's diagram the argument in the stimulus first.

Some 20th century art is great art.

XX - some-> great art

All great art involves original ideas.

Great art -> original ideas

We can infer from these two statements that:

XX century art some -> original ideas

Any art that is not influential cannot be great art.

~Influential -> ~ great art
Great art -> influential

We can combine these premises to say that :

Great art -> influential & original ideas

And can also infer that:

Influential <-some-> original ideas

We know that at least some art that is influential involves original ideas and vice versa - the overlap between these two subsets is great art.

We can also combine all three premises to infer that:

XX century art -some-> influential & original ideas

What (C) is trying to say is that:

IF art is influential THEN it must involve original ideas.

This inference is unsupported by the premises. We only know that art that is great involves original ideas and is influential and we know that some influential art involves original ideas (choice A) and vice versa, but we cannot that ALL art that is influential involves original ideas. Hence, we can conclude that (C) is the correct answer choice.

Let me know if this makes sense and if you have any further questions.