The simplest type of transport is
a diffusion
b exocytosis
c endocytosis
d facilitated diffusion

A Diffusion because Osmosis, which is also a form of passive transport, is similar to diffusion in that both move a substance from an area of high concentration to an area of low concentration.

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.