Why is dna called the "double helix"? select one: a. its structure was discovered by two workers, james watson and francis crick, a doubling of research effort at a building informally called the "helix" at cambridge university. b. dna is double stranded, with the two strands both in the form of a helix entwined around each other like strands of a rope. c. when dna interacts with rna, the two molecules form a twisted double strand. d. it seemed like a catchy name even though it has nothing to do with the structure of dna?