An effective thesis in an argumentative essay must
a. present both sides of the issue.
b. contain a quote from a source.
c. state a position on the topic.
d. include accurate statistics.

C. state a position on the topic.

Explanation:

You can use several writing tools to prove or contrast parts or your argumentation, for example, quote sources, consider the counter-arguments of your position or quote statistics, however the main objective of a thesis in an argumentative essay is to expose your position on the subject.

he is a confident leader.

the sentence that avoid faulty coordination is:

culture, which is well represented in philadelphia, plays a major role including theatre, music, and the visual arts.  

faulty coordination occurs when the writer gives equal importance two different ideas (clauses) which in fact are not equivalent. in order to correct a misplaced clause or idea, the writer can place less important or emphatic ideas in a relative clause as in the previous sentence.