* Yo no pude ir a clase ayer porque
enfermo (description)
estuvo
O estaba
era
fui

The answer would be estaba

The answer is estaba; fui Is preterite tense and Is not used for conditions/states,era is imperfect for ser but like fui isn’t used for conditions and estuvo is not in the yo form conjugation leaving estaba as your answer

Wouldn't it be the letter i? pretty sure it's i

Hola mis hermosos jóvenes