Question

Which of these has the correct version of "almorzar" used in the sentence.

Answer 1

Miguel fell to the floor in the past, which means that the eating also happened in the past. Therefore Horacio y Fernando ate in the past - we need a past tense.

almorzábamos is for first, not second person plural, so it's ungramatical.
almuerzan is present tense.

From the options, the best one is almorzaron, but actually you should rather use a continuous tense - almorzaban.

Answer 2

The second one "Horacio y Fernando almorzaron en la cafetería cuando Miguel se cayó al suelo." because almorzaron is past (and plural), and cayó is also past.