The correct answer is - A( Greece to the Indus River.
Alexander II of Macedon (Alexander the Great), during his reign created the biggest empire that the world had ever seen until than, and the Macedonian Empire was stretching on the area between the western parts of the Balkan Peninsula to the Indus River in the northwestern part of India.
Alexander III of Macedon was a genius military tactician, and very often, with much smaller army, managed to defeat the opposition. Also, there has to be given a big credit to his father, Philip II of Macedon, who reformed the Macedonian army and economy, and also managed to invade and put in control the biggest enemies of Macedon, the Greek city-states that despised them.
Note: I wrote from the western parts of the Balkan Peninsula, instead of Greece, because there was not a Greek country, but just city-states, so the western part of the Macedonian Empire were the territories of Macedon, Illiria, and Thessaly.
