20 points plus brainliest !

which best describes cosmic microwave background radiation?

radiation thought to exist but not yet measured
radiation predicted to exist in millions of years
radiation that existed before the big bang
leftover radiation from the big bang

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.

the water is warmed up by the sun and then it evaporates into the atmosphere. the sunlight warms the water by its heat. water is then cooled down and condensation takes place. the water then finally returns back to the earth by the process of precipitation in the form of rain or ice.

explanation: