List three methods that scientists can
use to develop organisms with desirable traits.

Um I don't know if this is what you're looking for but selective breeding, genetic modification, The manipulation of plasmids ,- Grafting branches  

Explanation:

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.