An angle of incidence of 20.0° in water results in an angle of refraction of 15°. a)Is the second medium more or less optically dense than the first medium?
b)Find the n of the second medium
c)Repeat this question for an angle of refraction of 25.0°

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.

c) up is the direction the magnetic force is acting on the charge.

it was given as a lesson and guide for prayer.