Which statement best relates to how the structure of a lipid influences the lipid’s function?
the ends of the lipid are attached to each other.
lipids contain fatty acids and glycerol.
a lipid is made up of a long chain of phosphorus molecules.
a phospholipid has a charged head and an uncharged tail.

I consider the second option represented above correct : A phospholipid has a charged head and an uncharged tail.The reason which led me to pick this one is that one of the options can be truse for oils, but anyway there wasn't mentioned anything about ways of how the structure can impact on the function. 
Do hope it will help you!

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .