Scientists think that convection currents flow in earth’s
a. continents.
b. mantle.
c. lithosphere.
d. inner core.
select the best answer from the choices provided.

Option B, Mantle

Explanation:

Mantle is formed out of molten magma. Magma is the inner core of earth that melts when movement occurs between the tectonic plates and the dense (heavy ) plate get subducted below the light plate there by generating convectional current in the mantle of earth. These convectional currents further drive the tectonic plates movement. Most of the convectional currents are thermal convection currents which arises when hot magma rises and cool magma sinks due to density difference.  

Hence, option B is correct.