(UNESC - 2018)
The correct passive form of "This town of 1,500 has acquired a unique status" is:
"A unique status:
have been acquired by this town of 1,500."
was acquired by this town of 1,500."
has been acquired by this town of 1,500."
was being acquired by this town of 1,500."
had been acquired by this town of 1,500."