Dear Kelsha16My name is Lily, I am an English tutor. I have received your question. I understand your confusion.Which sentence has the correct sequence of tenses?A. Before it became a federal prison,

Dear Kelsha16 Which sentence has the correct sequence of tenses?

My name is Lily, I am an English tutor. 

I have received your question. 

I understand your confusion.

Which sentence has the correct sequence of tenses?

A. Before it became a federal prison, Alcatraz Island serves as the site of a military prison.

B. Before it becomes a federal prison, Alcatraz Island served as the site of a military prison.

C. Before it became a federal prison, Alcatraz Island had served as the site of a military prison.

D. Before it becomes a federal prison, Alcatraz Island was serving as the site of a military prison. 

Please check my answer below