The space probe HEA1 returns to earth following a trip to the planet Tantoun. Analysis of samples from this planet reveals that proteins are composed of 16 different amino acids, while DNA contains only two bases: rosine (R) and ziadine (Z).

a) What is the minimum codon size in this genetic code? Explain your reasoning.

b) How many of the codons in this minimum genetic code will contain at least two Zs? Explain your reasoning.