Answers in bold and underlined.
Answer 1: . Hubieron tantos problemas el año pasado. Opción C.
Translation 1: There were so many problems last year. Option C.
Answer 2: Había muchos perros en el parque. Opción A.
Translation 2: There were many dogs in the park. Option A
Answer 3: Te espero desde hace una hora. Opción C.
Translation 3: I've been waiting for you for an hour. Option C.
Explanation on the subject:
The tense "hubo (had)" is used to talk about events or actions that happened in the past and are no longer happening. "Had" is used to talk about something that existed in the past, but no longer exists or has ended. "Since" is used to talk about something that has been happening for some time in the past and is still happening in the present.