Answer:
A. By the Democratic Party
Step-by-step explanation:
The 1968 Democratic presidential primaries were the selection process by which voters of several states elected delegates to the 1968 Democratic National Convention. Incumbent Vice President Hubert Humphrey was selected as the nominee in the 1968 Democratic National Convention held from August 26 to August 29, 1968, in Chicago, Illinois. (an exerpt from wikipedia)