Can you list your description options and I’ll help you from there?
The right answer is C. (non sens mutation are the most harmful)
In genetics, a nonsense mutation is a point mutation in which a nucleotide of a codon is changed, inducing the replacement of a codon encoding an amino acid (UGU, cystein) by a stop codon (UGA). The resulting protein, truncated and therefore incomplete (because the translation ends prematurely, and therefore we will have a truncated protein), is generally non-functional.
If they both have Rr. The possibilities will be RR, Rr, Rr, rr. They have a 25% chance of inheriting the recessive trait instead of their dominant trait. That means that these traits are hidden and not expressed in the previous generation.
A. after having cowpox they where immune to smallpox HOPE THIS HELPS