Convection occurs in fluids (so both liquids and gases, as well as rheids) and is the concerted, collective movement of groups or aggregates of molecules within the above through advection or diffusion or both at the same time. Convection can never take place in solids and is only specific to fluids.
The United States is an MDC.
Answer: 2) MDC or the second option.
The main crop would be corn because it's mostly warm there all year round!
