The number of human genes is almost the same as that of mammals such as cats and dogs, and is very close to that of rats. What is even more exasperating is that the number of rice genes is twice that of humans. What is the point of this passage? ['Mammals have similar numbers.', 'The number of genes does not represent the level of the species.', 'Humans and mice are genetically very close.', 'Some plants have more genes than animals.']