You’re right, it’s A ! the first one
The answer is A. It’s means to understand the lecture. So it wouldn’t be b, because it’ll say the students drink the lesson or c, because it’ll be the students read the lecture. You don’t read a lecture you listen. Nor d because you can’t do a lecture.
It is "saben" since it is talking about two people
Las playas de puerto rico son una parte importante del turismo de la isla
