Final answer:
The correct form is 'defending' because 'my brother' is a singular subject, calling for the verb to be in the third person singular form. Soldiers are pivotal in defending their nation against enemies and maintaining security.
Step-by-step explanation:
The correct sentence should be: "My brother is a soldier. He defends our country from enemies." The verb defends is in the present simple tense, which is used here to describe a general truth or a habitual action. Since 'my brother' is a singular noun, the verb must be in the third person singular form, which is why it ends in '-s'.
Soldiers are essential for a nation's defense and protection against enemies. Whether standing firm in desperate straits or protecting the homeland by forming alliances and waging great wars, they are trained and committed to defending their country's interests, sovereignty, and citizens. In history and the present day, defenders of nations take on the noble task of preserving freedom and security.