Final answer:
C. Three 'letters' or nucleotides of an RNA molecule are needed to code for a single amino acid, forming a codon. For measuring a handful of peanuts, grams would be the appropriate unit of mass.
Step-by-step explanation:
The student's question seems to be out of context, referring to the number of grams needed for an application to the hands, which is not related to the reference information provided. However, referencing the RNA and amino acid code question, the correct answer is that three 'letters' or nucleotides of an RNA molecule are required to code for a single amino acid. This set of three nucleotides is known as a codon. In the genetic code, each codon corresponds to a specific amino acid, and the sequence of these codons in an RNA molecule determines the sequence of amino acids in a protein.
When choosing the best unit of mass for measuring something like a handful of peanuts, one would generally use grams as the most appropriate unit. This unit is small enough to provide a precise measurement for the quantity in question, but not so small as to be impractical for everyday use.