All living creatures contain carbon
The correct answer is letter D. candela. The unit for measuring the rate at which light energy is radiated from a source is the candela. L<span>umen is the unit for measuring the total amount of visible light emitted by a source. Lux is lumen per square meter. </span>
<span>Gravity is an attractive force. All masses exert gravity, so matter pull toward each other. However, it is only significant when the masses are large, like that of Earth. Exactly what causes gravity still remains a mystery. Since all the other three fundamental forces (strong, weak, and electromagnetic) are caused by particles called bosons, some scientists think that gravity is caused by particles called the graviton. However, such a particle has not yet been observed, and its existence has not been proven yet.
Also, gravity does not hold EVERYTHING together, as another person has already mentioned. Static electricity holds your socks together after they come out of the dryer, not gravity. Also, gravity is too weak to hold together, say, the nucleus of atoms, or even atoms of molecules together.</span>