Some stimulants tend to reduce hyperactivity because they A) block the movement of inhibiting neurotransmitters. B) redirect the signals of neurons that excite other brain regions. C) boost activity in brain areas that increase attentivenes

Ghana, first of the great medieval trading empires of western africa (fl. 7th–13th century). it was situated between the sahara and the headwaters of the sénégal and niger rivers, in an area that now comprises southeastern mauritania and part of mali.