Since the new campus ..., it has grown to twice its original size.
opened a year ago
a year ago it opened
opening for a year
opens for a year
Present Perfect
Since + S. Past / waktu lampau → Present Perfect.
Maka, soal ini membutuhkan S. Past setelah kata since (S + V2 + O/C).
Bandingkan pilihanmu dengan sobat pembelajar yang lain.