Final answer:
The nearest star to our sun, Proxima Centauri, is at a distance of 4.3 light-years.
Step-by-step explanation:
The nearest star to our sun is Proxima Centauri and it is located at a distance of 4.3 light-years from us. A light-year is the distance that light travels in one year. Since light travels at a speed of approximately 300,000 kilometers per second, one light-year is equivalent to about 9.5 trillion kilometers.Therefore, the correct answer is a) Light-years as a unit of measurement when describing the distance between our sun and Proxima Centauri.