The Proclamation applied in the ten states that were still in rebellion in 1863, and thus did not cover the nearly 500,000 slaves in the slave-holding border states (Missouri, Kentucky, Maryland or Delaware) that had not seceded. Those slaves were freed by later separate state and federal actions.
The answer is <span>B. Gold could be traded for salt, which was used to preserve food and maintain health. </span>
I think it was the decimal system and concept of zero
