How do socialism and communism differ?

This is not in my own words i just searched . :

"While communism and socialism share many principles (in fact, some would say communism is an extreme form of socialism), the primary difference between the two is that communism is both an economic and political system, while socialism is only an economic system, and as such can exist within a number of political systems or even within parts of a larger economic system, such as capitalism. Other notable differences exist around the concepts of personal ownership (socialism maintains the concept of personal property ownership, while communism removes it) and personal choice (socialism maintains personal choice in areas like education and religion, while communism removes it)."

Hope this helps you :)

answer; i believe the correct answer is (a) the correlation between the cause variable and outcome variable is zero;