Which of the following situations is most likely to represent an illegal nonconforming use?

The situation that represents an illegal nonconforming use is a homeowner in a residential zone converting her residence to offices. This scenario involves a change in use that is not permitted under the zoning laws applicable to that area. Nonconforming uses are typically established uses that predate current zoning laws, allowing them to continue operating even if they do not conform to the current zoning regulations. However, the conversion of a residential property to commercial offices, such as in this case, is a clear violation of zoning regulations since it alters the intended use of the property from residential to commercial within a zone designated solely for residential use.

In contrast, the other scenarios involve variables that might not automatically classify them as illegal nonconforming uses. A commercial store in a residential zone may be an established nonconforming use if it existed before the zoning laws were enacted. A farmer expanding fields in an urban area could be adhering to agricultural zoning provisions, and a factory operating without necessary permits may not directly relate to zoning laws concerning land use but instead pertains to regulatory compliance for operations. Thus, the conversion of a residential property to commercial use represents a clear transgression of zoning and land use regulations, making it the most likely example of an illegal nonconforming use.