Final answer:
President Franklin D. Roosevelt's use of fireside chats was influenced by the emergence of radio as a popular medium in the 1930s. These chats allowed him to communicate directly with the American people, conveying his policies in a personal and reassuring manner, which significantly bolstered his popularity and presidential success.
Step-by-step explanation:
The context that influenced President Franklin D. Roosevelt's decision to use fireside chats was (a) the emergence of radio as a popular medium. Radio offered a direct and intimate way to communicate policies and ideas, and by the 1930s, most American families had a radio in their home. Roosevelt's fireside chats capitalized on this widespread listenership, allowing him to explain complex policies in simple terms and seek the public's support for his New Deal initiatives. This mode of communication highlighted Roosevelt's understanding of the power of the media and his ability to reach people directly in their homes, which contributed greatly to his popularity and the success of his presidency.
Roosevelt's adoption of radio for public addresses became an exemplary model for future presidents, who sought to use the prevailing mediums of their times, such as television, the Internet, and social media, to extend their influence and connect with citizens. His pioneering utilization of radio not only disseminated his messages broadly but also instilled a sense of reassurance and unity among the populace during tumultuous times, essentially expanding the scope of the presidency.