It was a joyous occasion when he came back from the war unharmed. a. solemn c. happy b. sad d. worrisome

Solemn is the answer because it means kind of relaxed

Doulingo is good. you can also watch movies that are in french, i am using this tactic  for japanese  and it a lot. listing to music with  french  lyrics would work well too because  you could absorb  the words while having fun.hope this ! : )