Thus the small differences distinguishing varieties of the same species, steadily tend to increase, till they equal the greater differences between species of the same genus, or even of distinct genera. (on the origin of species; chapter 4, p. 2) based on this context, the word genera most likely means select all that apply. specific type either gender same/similar family common characteristics

"Thus the small differences distinguishing varieties of the same species, steadily tend to increase, till they equal the greater differences between species of the same genus, or even of distinct genera."

Genera is plural for genus.  

Genus means biological classification of things that have common characteristics and can be divided into subcategories.  

Therefore, the correct answer is "same/similar family common characteristics."

* specific type

*either gender

*same/similar family

*common characteristics

Explanation:

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