How are the letters picked to depicted the genotypes of organisms in mendelian genetics?

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.

true                                                                                                       true true true true true true

ask your friends for what they got then copy it down if you don't have any friends which is fine than google it or pay the teacher