Question

What is true about the about the structure or function of the plasma membrane

Answer 1

I think it's D ..... a membrane may contain hundreds of different proteins. ... Some integral proteins have only one segment that covers the whole membrane, others cross several times.

Answer 2

The answer is C. The bilayer structure forms  a solid boundary that separates the cell from its environment.

Large molecules do not cross the membrane through vesicles but through carrier proteins. Option B. is entirely false as hydrophobic molecules never get in contact with water, they are 'water hating' unlike hydrophilic molecules.
The plasma membrane is made of both integral and peripheral proteins.

Hope it helped!