According to the fluid mosaic model of membrane structure, integral membrane proteins are primarily (Doudna 2010):

a) confined strictly to the hydrophobic later of the membrane.

b) positioned in a continuous layer across the entire inner and outer membrane     

c) Randomly oriented in the membrane with no fixed inside/outside polarity.

d) Embedded within a lipid bilayer. 

Integral membrane proteins are those that go through the entire membrane, which consists of both hydrophobic and hydrophilic regions, and thus, an integral membrane protein also needs to have those properties. Thus A is incorrect. The integral aspect of an integral membrane protein refers to the fact that it spans ONE entire membrane – not two different membrane, and thus B is incorrect. And lastly, the membrane is definitely polarized because the outside of the membrane is distinctly different from the inside (if it wasn’t then there would be no need to have a membrane), and thus, any integral membrane protein will DEFINITELY have some sort of polarity, which makes C incorrect. Thus, the correct answer is D.