Which sentence is punctuated correctly?
A. Baltimore which has a population of about 595,000 people, is the largest city in Maryland.
B. Baltimore, which has a population of about 595,000 people, is the largest city in Maryland.
C. Baltimore, which has a population of about 595,000 people is the largest city in Maryland.
D. Baltimore which has a population of about 595,000 people is the largest city in Maryland.