The input that is often the easiest to vary in the short run is usually__ A. Land or natural resources
B. Labor
C. Capital
D. Nine of the above; all recourses are fixed in the short run

Hi! after fertilization occurs, the zygote goes through mitosis and then differentiation (aka specialization of cells) to have a variety of cells that perform different functions. this allows for the creation of tissues and so on, all of which were once stem cells with no specific function.i hope i !