Cell A is more efficient at exchanging substances due to larger surface area to volume ratio.
Cell A is more efficient at exchanging substances with the surrounding environment than cell B because it has the larger surface-area-to-volume ratio. Larger surface area of the cell exchanges more substances with the surrounding environment while on the other hand, lower surface area of the cell exchanges less materials with the environment so we can conclude that cell A is more efficient at exchanging substances due to larger surface area to volume ratio.
well AU is only for inside a star system and the number of AU would be too high, so light years are easier its like saying ur 6 feet instead of 72 inches or in centimeters