Why is a river otter an environmental issue

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.

Explain how fossils scientists make discoveries about the lives of organisms and about how environments have changed over time. plz hurry up it time

Factors that can increase mutation rates a. high temps b. low temps c. food additives d. uv rays