Answer: i believe the answer is subject
Step-by-step explanation:
since foreign languages are the subject and learning is the verb therefore it has to be the subject. meanwhile, the other answers do not fit quite well to the answer, so when you are working with those types of things you have to look at the subject * basically what it's talking about.* and ask your self is this an object or this a verb and when you figure that out you well there's your answer!