The Illinois Radon Awareness Act requires:

A is incorrect because Illinois law does not require all homes to be tested for radon. While testing is recommended, it remains voluntary unless specifically required by a local ordinance or contractual agreement.

C is incorrect because the law does not assign responsibility for radon mitigation costs to buyers. Payment for mitigation is typically negotiable between parties and depends on the specific terms of the contract.

D is incorrect because 4.0 pCi/L is the EPA action level guideline, not a requirement under Illinois law. The state law focuses on disclosure rather than establishing specific legal thresholds.