Final answer:
Active transport moves materials from an area of low concentration to an area of high concentration, against the concentration gradient, and requires energy, typically ATP.
Step-by-step explanation:
Active transport involves the movement of materials against a concentration gradient, specifically from an area of low concentration to high concentration. This process is in direct contrast to passive transport, where substances move along the concentration gradient from high to low concentration. Active transport is considered active because it requires cellular energy, which is commonly provided by adenosine triphosphate (ATP). In this case, substances such as ions or molecules are moved 'uphill' in terms of concentration, which allows the cell to maintain internal conditions that are different from the external environment. Therefore, the correct answer to the student's question would be (b) From low concentration to high concentration.