Only farming one crop such as cotton is an example of:

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.

sound moves fastest in solids because the molecules are tightly packed and it allows sound to vibrate

the correct answer was location c, because earth is tilted away from the sun at this time