Janiya is taking a road trip the distance she plans to travel can be written as 3×10^2 kilometers, 3 ×10^5 meters, 3×10^7 centimeters or 3×10^8 milliliters. which distance unit uses the most appropriate unit? I think it's 3×10^5 meters

No, the distance unit that uses the most appropriate unit is "3 × 10^2 kilometers." This unit is the largest among the given options and is commonly used for long-distance road trips.