Al Brickett Had Two Mobile Homes on His Land Behind

Al Brickett had two mobile homes on his land behind his house. The mobile homes have been there since Al bought the land in 1971. In 1975, Al's area was zoned as R-1, an area for single family homes and no mobile homes. Suppose that Al removes the mobile homes for one year. He then buys new ones. The city finds Al in violation of zoning laws. Al:

A) Is in violation of city zoning laws.
B) Meets the requirements of a non-conforming use.
C) Did not meet the requirements for abandonment.
D) Can challenge the constitutionality of the violation.