B) The conquerors forced the populace to convert Islam.
Muslim expansion or the expansion of Islam began in the Arabian peninsula in southwestern Asia. It is the denomination that usually occurs to the military conquests or the trade reforms of the Arab Muslim civilization in which the Sassanid Empire, North Africa, and the Iberian Peninsula, including parts of the Byzantine Empire, would fall. Also included in this denomination is the influx of merchants in the Maghreb and in Africa, and missions made in the Philippines.
During the following centuries, Islam achieved several advances in other fronts, as in the rest of Central Asia, in Asia Minor, in southern Italy, in Eastern Europe, in Southeast Asia and in sub-Saharan Africa. However, all these advances were produced by different States independent of each other. While these advances were taking place, Islam was forced to retreat in Western Europe, especially by the so-called Spanish Reconquista. In the last third of the sixteenth century, a last Muslim state with universal pretensions, the Ottoman Empire, reached its maximum expansion.