An unenforceable restriction includes one which:

The correct choice identifies a scenario where an unenforceable restriction is present. Specifically, restrictions that prohibit ownership based on race are considered unenforceable due to the Civil Rights Act and various fair housing laws. Such restrictions are deemed discriminatory and violate fundamental principles of equality and fair treatment under the law, making them invalid and unenforceable in any real estate transaction.

In contrast, limitations based on economic status, inheritance within family lines, or zoning laws may be enforceable, provided they comply with local, state, and federal regulations. Economic status restrictions might be seen in entities like homeowner associations, family inheritance clauses are common in estate planning, and zoning laws are established by local governments to regulate land use and ensure orderly development. However, any restriction that discriminates based on protected characteristics such as race is inherently unenforceable under current legal standards.