Which event represents the time by when all of the slaves knew that they were freed?
a. the passage of the nineteenth amendment
b. the issuance of the emancipation proclamation
c. the delivery of the gettysburg address
d. juneteenth

The correct answer should be D. Juneteenth

The Emancipation Proclamation declared that slaves from all rebellious states were free from that point on, however, Texas was not a rebellious state and wasn't in the war so they still had slavery on a technicality. Juneteenth is a day in June when Texas abolished slavery and proclaimed that all slaves would be free in its territory, which was a sign that if they could do it then everyone can do it.