I believe the answer is: theory
Theory refers to the initial ideas that is used as an explanation for a certain principle.
Even though technically theory is just a form of guess that initiated before making the experiments, the guess is based on the general principles that accepted by most people in that field and could be changed depending on the available evidence.
<span>Political stability is not a barrier to economic development, so the correct answer is B. If something is stable, it means that it is in a good condition, and if it's in a good condition, it cannot be bad or preventing good things from happening. So B is a good thing, and cannot be a barrier to anything. Debts, diseases, and low levels of social welfare can be barriers, because they are indicators of bad conditions in a country. </span>
