When two genes from two different people are sequenced and aligned, it is discovered that there are multiple sequence differences in the coding segment DNA level. However, when the proteins formed by the genes have their amino acids sequenced, there is no difference observed between the two. What is the most likely explanation for this observation

On the basis of the phenomenon of the degeneracy of codons, the coding of single amino acid can take place by various codons like four different codons, that is, CCC, CCU, CCG and CCA can code for single amino acid proline.  

In case, if there is a mutation in DNA, due to which CCA get transformed to CCG, even in such case coding for the same amino acid proline will take place. Hence, one can conclude that at the level of DNA mutation is taking place, however, the same is not getting witnessed in a protein, and that is why such kind of mutations are termed as silent mutation.  

relative dating involves things like higher layers are most recent than rocks lower in the sequence. this can be extended to the known sequence of fossils. rocks containing rabbit fossils are later than those containing dinosaur fossils.  

absolute dating methods mainly use radioactive elements that have known rates of decay and produce recognizable products. for example potassium 40 decays to produce argon. once a rock has solidified the argon is trapped. by measuring the argon and potassium0 you can get an accurate number for the age.  

some other methods are good for archaeological ages. dendrochronology involves recognizing the sequence of tree rings. the orientation of magnetized particles in baked clay can be used to date a fire.

hope this .. .

answer; i believe that the correct answer is(d) nondisjunction during meiosis;