How does sickle cell disease protect against malaria

Which of the following is a limitation of a clinical trial? a.)amount of random assignments b.)hospital cost c.)number of test tubes d.)amount of peer review

Tom wants to conduct a scientific study but he needs to finish by the end of the school year. what practical way could tom work around this limitation and be successful in his study?

The structure of a dna molecule is best described as a. one long strand of nucleic acids b. two strands of dna nucleotides joined by hydrogen bonds c. two strands of amino acids joined by hydrogen bonds d. one long strand of amino acids