Final answer:
English diffused to North America during the late sixteenth century, with substantial colonization and migration in the seventeenth century, making the 15th century the correct period for initial diffusion. Option b is correct.
Step-by-step explanation:
English began to diffuse to North America around the late sixteenth century, following the age of exploration when England and France considered New World exploration and colonization.
The English were behind other European powers initially, but they established permanent settlements in the seventeenth century.
English colonization progressed with the establishment of colonies like Virginia, Massachusetts Bay, New Haven, and others where many English migrants arrived to populate the new lands.
Therefore, the correct answer to the question 'Around what time period did English diffuse to North America?' is b) The 15th century, although the most significant colonization efforts and migration waves occurred throughout the seventeenth century.