They believes studying behavior, the mind and circumstances leads to understanding people
gestalt
functionalism
structuralism
behaviorism

measure their densities same density, same sub

there is no correct list among the choices you've provided.

the list might look something like this:

-- baby human

-- piccolo

-- flute

-- soprano singer

-- trumpet

-- tenor singer

-- trombone

-- baritone singer

-- baritone horn

-- bass singer

-- tuba

since i had to make up the list myself, i made it easy on myself, and i didn't try to shuffle the string instruments and woodwinds into it too.

i believe the answer would be:

d. violin, clarinet, french horn, and tuba