To fit X-ray crystallographic data, the two DNA strands in Watson and Crick's model must be ____ to each other.

A) conservative
B) uncomplementary
C) parallel
D) antiparallel
E) semiconservative

Antiparallel

Said of a double-stranded nucleic acid in which the 5' to 3' direction of the sugar-phosphate backbone of one strand is reversed in the other strand.

Crystallographic Data

Information obtained from crystallography, a method used to determine the atomic and molecular structure of crystals, revealing the arrangement of atoms in the crystalline solid.

Watson

James Watson, an American molecular biologist, geneticist, and zoologist, best known as one of the co-discoverers of the structure of DNA in 1953.