To find the area of a rectangle, you multiply the length and width. In this case, the rectangle is 12 units long and 6 units wide.

So, the correct method would be:

C) Multiply 12 x 6

This will give you the area of the rectangle.

Explanation:
Area of a rectangle = length × width
Area = 12 × 6 = 72 square units.

Would you like more details or have any questions about this?
Here are some related questions you might find interesting:

1. How do you calculate the perimeter of a rectangle?
2. What is the formula for the area of a square?
3. How would you calculate the area of a triangle?
4. Can the area of a rectangle be negative? Why or why not?
5. How do you convert square units into different measurements (e.g., square inches to square feet)?

Tip: Always remember that the area of any polygon is calculated by multiplying dimensions (length × width, base × height, etc.).