What safety measures can employers use when workers are on a supported scaffold more than 10 feet above the working surface? a. top rail or guardrail b. personal fall arrest system or toeboard c. mid rail or toeboard d. personal fall arrest system or guardrail

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.