The only choice that would work is "subject" I guess. I'd use class, and that may be the American English word. If you are studying British English, then I'm not sure, but "subject" seems best.
To me ...
... lesson is a particular sub-topic being taught by a particular subject's teacher on any given day. Some teachers give more than one lesson during one particular classtime.
... subject is the discipline being studied (English, Italian, math, science, business...), but it's be best fit for your sentence if "class" is not a choice.
... course is the name of the class within the discipline. For example, in the broad discipline of Latin, there could be these courses: Latin I, Latin II, Caesar's Gallic Wars, Vergil's Aeneid, Cicero's Speeches, Medieval Latin, etc.
I urgently need you to answer this question:
1) Is class the American English for lesson?
Because students are asked to choose among three alternatives (one must be correct): a) lesson b) subject c) course
If your next ....... is chemistry, physics or biology, go to the labs (1st floor).
2 answers
should be: ... but it's the best fit ...