Name three intermolecular forces that stabilize the structure of dna, and explain how they act.

The correct answers are:

(1) nitrogen bases form hydrogen bonds to their complementary bases

This is true as adenine forms a double bond with thymine and guanine forms a triple bond with guanine. 

(2) sugar-phosphate chains form ion-dipole and hydrogen bonds to the aqueous surroundings

This is how the DNA is stabilized not only from inside forces but also from the environment in where the DNA is found.

(3) sugar-phosphate chains stack above each other, allowing for interaction through dispersion forces.

This is the mechanism on how the sugar-phosphate chains act as a backbone for the DNA molecule.

Well i had the same answer, so the correct answer would be a. but in this case it would be the one with plasma membrane and cell wall circled that is next to the hairy pill type of thing.