Final answer:
Option (a), The execution of King Louis XVI was influenced by economic instability, food shortages, social unrest, and popular uprisings.
Step-by-step explanation:
The execution of King Louis XVI during the French Revolution was driven by a combination of factors. Economic instability and food shortages were significant catalysts, intensifying the public's dissatisfaction with the monarchial system. Furthermore, the social unrest and popular uprisings that ensued created an atmosphere that demanded radical change and retribution against the perceived source of the turmoil, which was the ruling monarchy. As such, these events created the conditions that led to the king's execution and reflected broader calls for a new order that could address these systemic issues.
Regarding the causes of the American Revolution, British efforts to consolidate control over its colonies were a principal reason. These efforts by the British Crown incited resistance among colonists, ultimately culminating in their desire for independence. Such resistance was influenced by a variety of motives, including economic freedoms, political power, and territorial expansion, which united diverse groups in rebellion.