It seems to be character vs self since Claire is putting herself down with her insecurities.
The phrase in the excerpt from a 1964 interview with Malcolm X indicates that he is explicitly stating an opinion is this "<span>{I don't think that it} serves any purpose for the {leaders of our people} to waste their time fighting each other needlessly."</span>
To prevent from succeeding.
<span>Macbeth's mind is full of self-doubt. Lady Macbeth's death is a result of her guilt at her part in having killed King Duncan.</span>
When you enumerate you need to put comas between all the items except the ones which are connected by "and" : as A is not correct as it does not have comas, and B is incorrect as it has comas where "and" is.
now, in a way both C and D are correct, but C is the usual accepted version, and D is an example of "Oxford coma" (where the coma is optional, to remain on the safe side, choose C).