The paragraph basically states that -

Most people's concept of good life is different from that of every moral theory developed in the Western tradition.

The option that closely resembles this has to be the correct answer.

Option A -
the argument clearly states this -
good life -- the kind of life they would want for themselves and their children.

We know that most people want a good life for themselves and their children. We have no idea whether they want something better than a "merely" good life.
hence, Incorrect.

Option B -
We cannot make this assumption. It is perfectly possible that all those theories agree on ideals. hence, incorrect.

Option C -
Closely resembles the argument and hence is the correct answer.

Option D -
We only know that most people would disagree with those moral theories on what a good life is. We have no idea whether good life as espoused by those theories is realizable or not. Hence, incorrect.

Option E -
Cannot be inferred. Moreover, this talks about all theories, not just theories developed in the West. Hence, not relevant and incorrect.