In the Watson-Crick model of DNA, the "sides" of the ladder are composed of

A) sugars.
B) bases.
C) hydrogen bonds.
D) sugar-phosphate molecules.
E) phosphate groups.

Watson-Crick Model

A structural model of DNA proposed by James Watson and Francis Crick, illustrating DNA as a double helix composed of two antiparallel strands.

Sugar-Phosphate

Refers to the backbone of DNA and RNA, composed of alternating sugar and phosphate groups that hold together the nucleotide bases.

Ladder

A piece of equipment consisting of a series of bars or steps between two upright lengths of wood, metal, or rope, used for climbing up or down.