Marathon runners: a. only eat carbohydrates. b. tend to have more slow-twitch muscle fibers. c. are always very thin. d. can one or two marathons a year

Why do rna viruses appear to have higher rates of mutation? a) rna nucleotides are more unstable than dna nucleotides.b) replication of their genomes does not involve proofreading.c) rna viruses can incorporate a variety of nonstandard bases.d) rna viruses are more sensitive to mutagens.