Answer:
The correct answer is Hace un año.
Step-by-step explanation:
In this case we have a reading comprehension activity. The best thing you can do is read the text as many times as necessary until you fully understand it. You can always help you with a dictionary or a translator.
As for the question, you're being asked "How long ago?" ...
What in English we would respond with : "xxx time ago / xxx weeks ago", etc
In Spanish we respond: Hace xxx. (Hace un año, hace una semana, hace un mes, hace un día, etc).