Answer:
A: Hay siete días en una semana.
Step-by-step explanation:
The question asks: "How many days are there in a week?"
The options are:
A: Están siete días en una semana.
B: Son siete días en una semana.
C: Hay siete días en una semana.
D: Hayan siete días en una semana.
The second and third answers are singular, which rules them out.
Hayan roughly translates to have (plural). Están roughly translates to "there are", which makes it our answer.