What's that story, Was it the "The eyes were watching god?"
The correct answer should be A: there is no single best career path.
Sure if you want to become an actor you have higher chances if you go to an acting school, for example, but there have been countless examples of non-schooled actors who just went to auditions or who worked as waiters and got seen in a restaurant and were hired. You should always keep your eyes open for all options.
Common good means for the good of the public or the many. One example of a scenario of contributing to the common good is that a person follows the laws of the country like traffic. It is a common good because following the rules will give order thus contributes to the common good while not following the rules only served the person own's interest.
I think the answer should be A.
Hope this Helps! :)