Final answer:
The printing press is the key development that distinguishes Early Modern English. It facilitated the spread of the Renaissance and Humanist ideas and reshaped authority by enabling mass production and distribution of texts.
Step-by-step explanation:
The key development that distinguishes Early Modern English is A) The printing press. The introduction of the printing press to Europe by Johannes Gutenberg in the mid-15th century revolutionized the spread of knowledge. For the first time, information could be mass-produced and distributed efficiently, making texts and ideas more accessible and leading to intellectual movements such as Humanism. The printing press played a pivotal role in advancing the Renaissance, facilitating the dissemination of Greek and Roman classical texts and empowering reformers like Martin Luther to publish works that would deeply influence the Protestant Reformation.
Through the printing press, people's ideas about authority and the church were significantly altered, contributing to the development of European nation-states. The capacity to print books and share knowledge widely enabled critiques of established authorities and supported a growing skepticism which was an essential part of the Humanist philosophy of the Renaissance.