The answer is D.
Factor production that could be changed during particular period is called Variable Factor of Productions.
Basically, factor of productions is divided to fixed and variable factor.
FIxed factors are the one that will always stay the same no matter how many products you made. For example electricity cost, building rent, etc
The variable factors differ depend on how product you produce, such as raw material.
Answer:
This made double-cropping possible in some areas, and in some places, even triple-cropping became possible ... the hardiness and productivity of various varieties of rice were and are in large part responsible for the density of population in South, Southeast, and East Asia.
I know this for 100% it is A. they're convenient , I know this one for sure 100% positive hope it helps
Water is not made artificially, so when we get rid of water or pullute it, we are losing that natural recource, therefore making it limited.
