Unlike food webs, food chains
a. involve a single chain of energy transfer from one organism to another through consumption
b. contain autotrophs that make their own food
c. involve a network of complex interactions among various organisms in an ecosystem .
d. contain consumers that eat producers .

The correct answer is A. 

a food chain might look like this: plant —> bird —> mammal
while a food web would look more like a spider web, and get it's energy from multiple sources. The network explained in choice C is a food web. Answer choice B and D are also false because both food webs and food chains contain autotrophs… 90% of our energy is from the sun, and the only way to get that energy is through the consumption of autotrophs. 

Because the earth is not round ,but it may seem round when viewed from ,our planet but true some points earth is not round was an oblate spheroid -a square that it squashed as globe however is not even a perfect oblate spheroid.in fact isaac newton's first proposed that earth was not perfectly round but it was an oblate spheroid instead.that mean a square that is squashed as its poles and swollen at the