Where is your diaphragm located?

a.
below your rib cage
b.
underneath your trachea
c.
above your lungs
d.
behind your heart

The diaphragm is locate just under your lungs and above oyour liver

It's A! Below your ribcage! (: It's just underneath. You may hear the phrase "sing from your diaphragm " they're just expressing that you should sing down deep! (: Technically, it's more so a phrase because if you attempt to sing from your diaphragm there's a bunch of muscle tightening, and definitely not comfortable!
I hope all is well, and you pass! (: Good luck, rockstar!

Efficiency is an act of doing something

Is a  vector quantity  that refers to "the rate at which an object changes its position." imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. while this might result in a frenzy of activity, it would result in a zero velocity. because the person always returns to the original position, the motion would never result in a change in position. since velocity is defined as the rate at which the position changes, this motion results in zero velocity. if a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. every step must go into moving that person further from where he or she started. for certain, the person should never change directions and begin to return to the starting position.