Final answer:
The answer is option A. The difficulty in deciding how to select a president arose from regional differences and concerns about state representation. Other key issues included the impact of slavery on representation and the balance of power between federal and state governments.
Step-by-step explanation:
The factor that made it difficult for the framers of the constitution to decide how to select a president was primarily a) Regional differences and the question of state representation. The debate encompassed several key issues, including the balance of power between large and small states, the concern over governmental abuse of power, and fears of mob rule, as exemplified by Shays' Rebellion. The framers wanted to avoid both an excessively powerful central government and an executive who could potentially behave like a monarch.
Furthermore, the framers had to consider concerns about slavery and its impact on representation, the separation of powers, and checks and balances within the federal government. Eventually, the framers reached a compromise that led to the creation of the Electoral College, which aimed to balance the influence of large and small states and maintain a degree of separation from Congress in the election of the president.