Is the clause in parentheses an adjective or adverb clause The guinea hens (that my neighbor raises) are better than watchdogs.?

The clause in parentheses, "that my neighbor raises," is an adjective clause. It modifies the noun "hens" by providing more information about which guinea hens are being referred to. Adjective clauses typically answer questions like "which?" or "what kind?" and this clause specifies the type of guinea hens.