For the data table below, identify a column or group of columns that make up a candidate primary key:

first_name	last_name	street_address	city	state	postal_code
John	Smith	79873 Hudson Alley	Washington	District of Columbia	20566
Mary	Smith	79873 Hudson Alley	Washington	District of Columbia	20566
Darcy	D'Alessandro	6777 Hanson Center	Lancaster	Pennsylvania	17622
John	Smith	147 Memorial Junction	Indianapolis	Indiana	46216

A.first_name + last_name

B.first_name + last_name + street_address

C.last_name + postal_code

D.street_address