Which of the following is an example of active transport?

 The correct answer is Option (4) -Sodium and potassium pumps

The Sodium-potassium pump, located on the cell membrane, exemplifies active transport. This mechanism expels 3 sodium ions from the cell exterior and brings in 2 potassium ions for every ATP molecule consumed.

Cells employ active transport to amass essential molecules like glucose and amino acids. Active transport, driven by adenosine triphosphate (ATP), is termed primary active transport. Conversely, transport relying on an electrochemical gradient is labeled as secondary transport. Transport that uses an electrochemical gradient is called secondary transport.