The correct option is C All of the above.
Botanical nomenclature is the formal, scientific naming of plants. The principles and rules are listed in international code of botanical nomenclature (ICBN). According to ICBN, the colour of the flower is not a criteria for classification.
A tautonym is a scientific name of a species in which both parts of the name have the same spelling. In the current rules for botanical nomenclature (ICBN), tautonyms are explicitly prohibited. According to ICBN, two genera can not have the same name. Thus, option D is correct.