Why is it important that the phospholipid bilayer be both hydrophobic and hydrophilic?

it is not important

to maintain a proper internal environment

to link cells together

The answer to your question is:  The second option is correct.

Explanation:

Pospholipid bilayer is a thin lipid layer that protects and isolate the cell from the enviroment, also it controls the the entrance of molecules to the cell  and ejects wastes. So it is extremely important.

it is not important    This could not be the right answer, bilater is very important.

to maintain a proper internal environment  I think this is the right answer because among others, membranes mantain a proper internal environment.

to link cells together This option is incorrect, because membranes do not link   cells.

the median of the data is 4.5.