One reason for the growth of the national government’s power and influence has been a. heightened expectations and demands placed on the federal government b. the failure of the states to provide adequate opportunities for interest group participation c. the gradual expansion of the national share of the property tax d. the trend among democratic countries to become more unitary

a.

Explanation:

Based on the information provided within the question and past experience, it can be said that this is mostly caused by heightened expectations and demands placed on the federal government. These expectations and demands cause governments to take action in order to meet the demands, which lead to gaining power and influence as those actions unfold. Which has been known to be the case throughout history.

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