I need help with this question plz and thank you

6. in the dna double helix, how are the two strands of dna held together? a. chemical bonds between base pairs hold the two strands of dna together. b. hydrogen bonds between the base pairs hold the two strands of dna together. c. hydrogen bonds between sugar groups and phosphate groups hold the two strands of dna together. d. chemical bonds between sugar groups and phosphate groups hold the two strands of dna together.

__1__ is a climate cycle where the temperature of the __2__ ocean changes because of movements of air and ocean currents. during this period, the trade winds in the south __3__ , causing the __4__ water to move from the __5__ region to the __6__ region. 1) el nino or the monsoon 2) atlantic, indian, or pacific 3) reverse, strengthen, or weaken 4) cold or warm 5) eastern or western 6) eastern or western

What was photo 51 with rosalind franklin?