Hey there,
Your question states: Which of the following is not a barrier to economic development? Your correct answer would be "political stability" because it is not in good condition. The other options are really bad things that are happening around. For e.g: "widespread diseases" are not good. Also, "low levels of social welfare" is not good. The only good thing that is here is a "political stability" and the question is asking "Which of the following is
a barrier to economic development?
Clarifying your answer would be B.) Political Stability
Hope this helps!
~Jurgen