What is the distance formula between two points (x1, y1) and (x2, y2)?

• A. u221A[(x2 - x1)^2 + (y2 - y1)^2]
• B. [(x1 + x2)^2 + (y1 + y2)^2]
• C. (x2 - x1) + (y2 - y1)
• D. None