The correct answer is:
B. The rate remains the same, even if income increases or decreases.
Explanation:
In a proportional tax system, also known as a flat tax, the tax rate stays constant regardless of the individual's income level. This means that as income increases or decreases, the percentage of income paid in taxes remains the same. For example, if the proportional tax rate is 10%, someone earning $10,000 would pay $1,000 in taxes, and someone earning $100,000 would pay $10,000 in taxes, maintaining the 10% rate. This distinguishes it from a progressive tax system where the tax rate increases as income rises, or a regressive tax system where the tax rate decreases as income increases.
