Step 1: Concept
The fall of empires is often attributed to a combination of internal and external factors. For the Mauryan Empire specifically, historians have identified various causes that contributed to its decline.
Step 2: Meaning
In this context, we need to evaluate which options are generally considered significant reasons for the fall of the Mauryan Empire based on historical analysis.
Step 3: Analysis
Weak successors of Ashoka (A): After Emperor Ashoka's reign, his successors were not as effective or capable. This internal weakness is a well-documented factor in the decline.
Excessive deforestation (B): While environmental issues can impact societies, there is no strong historical evidence to directly link excessive deforestation with the fall of the Mauryan Empire.
Heavy expenditure (C): The empire's financial strain due to extensive military campaigns and other expenditures could have weakened its resources over time.
Invasions of Huns (D): The Hun invasions occurred much later, around 450 CE, long after the fall of the Mauryan Empire in 185 BCE. Thus, this is not a relevant cause for the Mauryan Empire's decline.
Militant Brahmanical reaction (E): There were indeed conflicts between the Mauryans and certain religious groups, but these are more likely to have been internal political struggles rather than direct causes of the empire’s fall.
Step 4: Conclusion
Considering historical analysis, weak successors, heavy expenditure, and militant Brahmanical reactions are generally recognized as significant factors in the decline of the Mauryan Empire.
Final Answer: (C)