Final answer:
Option (A), Suleiman the Magnificent (Suleiman I) was the Sultan who expanded the Ottoman Empire to its peak size during his reign from 1520 to 1566.
Step-by-step explanation:
The Sultan who expanded the Ottoman Empire to its largest area was Suleiman the Magnificent (Suleiman I). He reigned from 1520 to 1566 and under his rule, the empire witnessed significant territorial expansion. His conquests included the capture of Belgrade in 1521, Hungary in 1526, and he pushed the empire's frontiers into Europe, the Middle East, and North Africa.
Suleiman also solidified his rule by establishing a comprehensive legal system and facilitated the flourishing of science within the empire. His military might and strategic governance set the foundation for an empire that, at its peak, was considered the most technologically advanced in the Mediterranean world, challenging powerful European states.