Ruan Is Making Potato Soup

Ruan is making potato soup. His roommate tastes it and tells Ruan it is great, but Ruan thinks it needs more salt. He adds just a little salt, and thinks the soup now tastes perfect. However, his roommate tastes it again and tells Ruan that the soup is ruined because it is too salty. Apparently, for the taste of salt

A) Ruan can detect a smaller just noticeable difference than his roommate.
B) Ruan's roommate can detect a smaller just noticeable difference than Ruan can.
C) Ruan has a higher absolute threshold than his roommate does.
D) Ruan has a lower absolute threshold than his roommate does.