Answer and Explanation:
To change "alemán" (German) into the appropriate adjective form of the sentence: "Mi tía es..." (My aunt is...), you would use the feminine form since "tía" (aunt) is a feminine noun.
The adjective form of "alemán" for a feminine noun is "alemana."
So, the complete sentence would be: "Mi tía es alemana," which means "My aunt is German".