You Have Four Friends

You have four friends. Which of your friends can be described as "frictionally unemployed"?

A) Mona, who recently went on medical leave from her work
B) Davis, who wants to work as an automation engineer but finds that he is required to get additional certification to qualify for available automation engineer jobs
C) Francis, who works part-time at the skating rink until he finishes his training as a snake handler
D) Melia, who is has been looking for work for nine months but now believes that there are no jobs available