Answer:
malade 
Step-by-step explanation:
heureux means happy 
ennuyé means bored
préoccupé means concerned 
malade means sick 
hence to fill in the blank the most appropriate option is "malade - sick"
 If you are sick, you should go to the doctor.
in french , it would be : 
 ---Si vous êtes malade, vous devriez consulter un médecin.