Conclusion needs to be drawn only from the passage given.

Option A - Incorrect
The passage only mentions the increasing rate of income inequality among Gublandians which further leads to the decreasing rate in their average salary. It doesn't mention if it has a positive or negative effect on the country's economy.

Option B - Incorrect
This answer choice makes a too-far leap in logic generalizing that all the labor force of Gublandia is experiencing hardship whereas the passage only talks about the fluctuation in the income and average salary of Gublandians. It can't be known from the passage whether or not the entire labor force is experiencing hardship.

Option C - Correct
Since the income inequality and average salary of Gublandians are continually increasing and decreasing respectively, we can infer that more than 90% of Gublandia's resources are controlled by 10% of the population.

Option D - Incorrect
There is no claim or statement from the passage to validate this assertive.

Option E - Incorrect
This answer choice only references the income inequality of Gublandia as a nation, while the passage specifically discusses income inequality among Gublandia citizens. So, we cannot make inferences based on this information given.