What was a key element in developing a market economy in nineteenth century america
a) creating a system of toll roads to generate a federal revenue
b) improving roads to transport goods
c) retooling the conestoga wagon to carry a heavier load
d) developing a merchant marine to promote water transport

A key element in developing a market economy in nineteenth century america was "B) Improving roads to transport goods," since without these routes of transport business was "stuck" in only certain areas. 

The  pan-african movement  was an "emotional, cultural, psychological and ideological  movement  that began among the  african  dispora in the western hemisphere, for a closer  purpose, so that  african  people could feel secure, attain political, economic as well as psychological power visa vis other races or world regions" .