Answer: Option (c) is the correct answer.
Explanation:
A long hydrocarbon chain that consists a terminal carboxylic group is known as a fatty acid.
An unsaturated fatty acid consists a double bond within the fatty acid chain. If a fatty acid contains more than one double bond then it is known as polyunsaturated fatty acid.
For example, oelic acid has chemical formula 
is an unsaturated fatty acid.
Therefore, we can conclude that option (c) represents an unsaturated fatty acid.
Answer: C: Neurons that analyze and respond to specific types of input.
Explanation:
It wasn't that the favourable traits were passed down through generations of species, it's that natural selection removed the species who simply couldn't survive. Here's an example: There are two species of moth in a forest, one is brown and the other is black. The trees in the area have trunks that are brown like the moth's wings, so it can camouflage very well compared to the black moths. Eventually, more black moths were being eaten by various amphibians and bugs than brown moths. So, the favourable trait of brown wings continued to be passed on, whereas the black wings went extinct as they were all eaten. Hope that helped :D
Answer:
C) They should send signaling molecules across a small extracellular space.
Explanation:
To send a message to nearby cells, signal molecules only need to cross a small amount of space. Bloodstream (choice A) is used for long-distance communication, choice D is too vague, and choice B is used only for cells that are directly touching each other.
