These three apply:
Most lakes and waterways were considered neutral.
The Congo would stay in Belgian hands.
Slave trade was prohibited.
"Slave trade allowed" obviously doesn't stand, because slave trade was prohibited.
"Africa would be divided among European nations and America" seems a bit of a decoy answer. If it just said, "Africa would be divided among European nations," then it would be true. But adding America to the mix isn't correct. The Berlin Conference involved European powers.
