The correct answer is B. 120 degrees.
The central angle of a sector is the angle formed by the two radii that intersect at the arc of the sector. The ratio of the central angle $\theta$ to $360^\circ$ is equal to the ratio of the arc length $s$ to the circle’s circumference $c$. In this case, the arc length is the amount of income tax paid, and the circle’s circumference is the total income.
The average income tax rate in the United States is 22%. If we assume that the average income is $50,000, then the amount of income tax paid is $11,000. The circumference of a circle with radius 50 is $2\pi r = 2\pi (50) = 314.159$. Therefore, the central angle of the sector representing income tax is $\theta = \frac{s}{c} \times 360^\circ = \frac{11,000}{314.159} \times 360^\circ \approx 120^\circ$.
Option A is incorrect because it is the central angle of a sector representing 10% of the total income. Option C is incorrect because it is the central angle of a sector representing 15% of the total income. Option D is incorrect because it is the central angle of a sector representing 20% of the total income.