Final answer:
The distance from Alice Springs to Darwin by road is approximately 945 miles, therefore the correct answer is option a. 945 miles.
Step-by-step explanation:
The journey from Alice Springs to Darwin is a significant one as both cities are located in the Northern Territory of Australia but are quite far apart. The actual distance of this journey in miles is a detail that requires knowledge of the regions' geography and the Australian road network. After checking the distance on a reliable map or using geographic information systems, one can confirm that the distance from Alice Springs to Darwin by road is approximately 945 miles (around 1520 km).
Therefore, the correct option for the distance the citizens must travel from Alice Springs to Darwin in miles is: a. 945 miles.