Answer:
D). It suggests a reason why the call to action is attainable.
Step-by-step explanation:
In the given paragraph, the author states a call of action in the first sentence that 'We must go for our daily businesses more determined especially when we discover a way to do something extra in our community to help others, to build morale, to give a feeling of security, we must do it.' The third sentence proposes a reason stating that the above call of action is achievable when it states that 'we are the unconquerable people of America' which implies that the people of America can and will pursue this call of action with complete strength and determination to help the community as they are resistant to the difficulties. Thus, option D is the correct answer.