In this question, we have a square of length 4 units, inside which a circle is drawn. The shaded portion refers to the area outside the circle, but within the square.

To find the area of the shaded portion, we need to find the area of the square and subtract the area of the circle.

The area of a square is calculated by multiplying the length of one side by itself. In this case, the length of the square is 4 units, so the area of the square is 4 * 4 = 16 square units.

The area of a circle is calculated using the formula A = πr^2, where A represents the area and r represents the radius of the circle. Since the circle is drawn inside the square, the radius is half the length of one side of the square, which is 4/2 = 2 units. Plugging this value into the formula, we get A = π * 2^2 = 4π square units.

Now we can find the area of the shaded portion by subtracting the area of the circle from the area of the square: 16 square units - 4π square units = 16 - π square units.

Therefore, the correct answer is option 3: 4