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.