The three characteristics into which the modern era can be divided are:
a. The ‘early period’ which ended with the arrival of the Industrial Revolution in the mid-18th century.
b. The 18th century Enlightenment, and the Industrial Revolution in Britain, posited amid the dawning of an ‘Age of Revolutions’, beginning with those in America and France, and then pushed forward in other countries partly as a result of the upheavals of the Napoleonic Wars.
f. The contemporary era commences with the end of the revolutions of the 19th century, and includes both world wars and the cold war.
These options reflect important developments and phases within the modern era while the other options either mischaracterize this period or are not widely recognized divisions within it.