Final answer:
The principal meridians in Illinois are the 2nd and 3rd only. These are utilized for land division within the Public Land Survey System.
Step-by-step explanation:
The principal meridians located in Illinois are the 2nd Principal Meridian and the 3rd Principal Meridian. Therefore, the correct answer to which principal meridians are located in Illinois is b) 2nd and 3rd only. Principal meridians, along with base lines, are used in the Public Land Survey System to help divide and identify land in the United States. Specifically in Illinois, many land descriptions reference the 2nd or 3rd Principal Meridian.