Final answer:
The correct nominative singular endings for the third declension adjective 'brevis, breve' are 'brevis' for the masculine/feminine and 'breve' for the neuter, making the correct answer 'brevis, breve'.
Step-by-step explanation:
The correct nominative endings for the singular form of the third declension adjective brevis, breve are brevis for the masculine/feminine form and breve for the neuter form. Therefore, the right answer from the given options is brevis, breve. In Latin, adjectives of the third declension have a single ending for both masculine and feminine forms in the nominative singular and a distinct ending for the neuter form.