Answer: The answer is (a). The average cost of producing electricity nationally is rising.
Step-by-step explanation: We are given three options and we are to select which one is the macroeconomic issue among them.
A macroeconomic issue is one that helps in solving economic problems like poverty, unemployment, inflation, deflation etc. For such macroeconomic problem, the solution is possible at macro level only.
Looking at our options, we can see that options (b) and (c) are more or less domestic as compared to the first option, which is related to a national or global issue.
Thus, the correct option is (a).