The answer is rubric. Hope this helps.
The volunteers for the event are them; predicate nominative.
The correct answer is "The Pony Express delivered messages on horseback through many areas". The introductory paragraph is a specialty paragraph that introduces the reader to an essay. An introductory paragraph contains a topic sentence, which defines the topic; the thesis sentence, which defines the writer's point of view; and the outline sentence, which describes the main topic.
