Match the following. duration
1. type of exercise
mode
2. how often an exercise is performed
frequency
3. amount of time needed to perform an exercise
intensity
4. level of effort needed to perform an exercise

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.