Cual es la importancia del idioma en un determinado contexto

Fill the blank with a la, a los, a las, or al. los alumnos

Need with this match the pronoun with the sentence it belongs to: )

Okay so i'm taking an online spanish course (penn foster), and in the study guide, you have to create a bunch of sentences with words you've learned so far. translating, reading, and those kinds of things are fairly easy, but when it comes to making my own sentences, my brain just kinda waltz's away. anyone got any tips?