Question

which of the following sentences is not grammatically correct? las bisabuelas no son jóvenes. la bisabuela no es joven. el bisabuelo no es joven. los bisabuelos no son joven.

Explanation:

To determine the grammatically incorrect sentence, we analyze subject - verb - adjective agreement in Spanish.

• "Las bisabuelas no son jóvenes": "Las bisabuelas" (plural feminine subject) agrees with "son" (plural verb) and "jóvenes" (plural adjective).
• "La bisabuela no es joven": "La bisabuela" (singular feminine subject) agrees with "es" (singular verb) and "joven" (singular adjective).
• "El bisabuelo no es joven": "El bisabuelo" (singular masculine subject) agrees with "es" (singular verb) and "joven" (singular adjective).
• "Los bisabuelos no son joven": "Los bisabuelos" is a plural masculine subject, so the adjective should be plural ("jóvenes") to agree with the plural subject and verb "son".

Answer:

Los bisabuelos no son joven.