Which of the following must be disclosed to a party in a transaction?

The requirement to disclose the presence of lead-based paint on the property stems from federal regulations designed to protect public health, particularly for children under the age of six, who are at greater risk for health hazards associated with lead. The Residential Lead-Based Paint Hazard Reduction Act mandates that sellers and landlords inform potential buyers or tenants about known lead-based paint and lead-based paint hazards in homes built before 1978. This is crucial because lead exposure can have serious health implications, and potential buyers need this information before making decisions about the property.

While the other options may involve significant information, they do not carry the same legal obligation for disclosure mandated by federal law. For example, future development plans, while potentially impactful on property value, are often speculative and not always disclosed unless they directly affect the property in question. Likewise, the duty to disclose all offers received by the seller varies based on local laws and the specifics of the agency relationship, and inspection reports may be shared at the discretion of the seller but are not required disclosures. Thus, the presence of lead-based paint is the only option here that falls under federally mandated disclosure requirements.