Thermal energy tends to flow as heat
A. from a system of lower energy to a system of higher energy.
B. only between systems that have equal energy.
C. only between systems that have equal temperatures.
D. from a system of higher energy to a system of lower energy.

D. from a system of higher energy to a system of lower energy; this is due to the zeroth law of thermodynamics, which states that when two objects are placed in contact heat (energy) is transferred from one to the other until they reach the same temperature (are in thermal equilibrium).

the correct answer is - d. china has a large and growing population.

the fact that china has a large (the biggest) population, and it is still growing, doesn't hinder the agriculture production in the country. in fact, it can for increased production in the agriculture, since there's more labor force, as well the sheer mass of people produces lots of scientists that come up with new inventions as to how to improve this sector. nice example is the inner mongolia region in china, in general dominated by the gobi desert, but few scientist came up with a nice idea as to how to make the region productive by using plants that are very resistant to droughts, so lots of people have been employed, and the region is becoming greener and greener each year, and the production of food in this region is also increasing.