Final answer:
The correct unit to measure the distance from LA to Chicago is Option A) kilometers.
Step-by-step explanation:
When considering the measurement of the distance between two large locations, such as from LA to Chicago, one needs to consider the most practical unit of measurement. In this case, kilometers (km) would be the most suitable unit. Kilometers are commonly used to measure long distances much like the distance between LA and Chicago. Miles could also be used, considering the context, especially within the United States. However, among the options provided, the best choice would be Option A) kilometers.