Evidence of a chemical change can be observed when- A. a solid melts into a liquid.
B. cookies are crumbled.
C. a drink is poured from a can to a cup.
D. a banana turns brown after being cut.

A. a solid melts into a liquid

Explanation:

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 answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.