Friction always acts in a direction to the motion. a. parallel b. equal c. similar d. opposite

Friction always acts in a direction opposite to the motion.

This is another way of saying that friction always takes energy away from motion.  It never gives motion additional energy.

e) none of the above answers are correct

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.