Which best describes the Persians' rule?

The Persians were only vengeful if you're one of those that take the Bible literally and disregard all other historical evidence. Bible thumpers think the Romans were cruel too, but both the Romans and Persians were among the most tolerant empires in history.

The Persians were very interested in empire, and they certainly weren't the world's best sailors. That distinction should go to either the Athenians or the Phoenicians, who are in my opinion the better choice. The best answer here, although certainly not the one the asker is actually looking for, is B, they were monotheists. While that isn't actually true it's the one that is the least wrong. The Persian empire did ascribe to a largely monotheistic religion, Zoroastrianism, in addition to their polytheistic beliefs.

The first of these was the Achaemenid Empire established by Cyrus the Great in 550 BC with the conquest of Median, Lydian and Babylonian empires. It covered much of the Ancient world when it was conquered by Alexander the Great