Your answer, "One", is not correct.
The correct answer to
How many were possessed with devils?
is
Two
as shown by
Matthew 8:28-31
which is
- KJV
- [28] And when he was come to the other side into the country of the Gergesenes, there met him two possessed with devils, coming out of the tombs, exceeding fierce, so that no man might pass by that way. [29] And, behold, they cried out, saying, What have we to do with thee, Jesus, thou Son of God? art thou come hither to torment us before the time? [30] And there was a good way off from them an herd of many swine feeding. [31] So the devils besought him, saying, If thou cast us out, suffer us to go away into the herd of swine.
- NIV
- [28] When he arrived at the other side in the region of the Gadarenes, {Some manuscripts Gergesenes; others Gerasenes} two demon-possessed men coming from the tombs met him. They were so violent that no one could pass that way. [29] "What do you want with us, Son of God?" they shouted. "Have you come here to torture us before the appointed time?" [30] Some distance from them a large herd of pigs was feeding. [31] The demons begged Jesus, "If you drive us out, send us into the herd of pigs."