Question: The Great Plains lie west of the Mississippi River and east of the Rocky Mountains. A large portion of the country's agricultural products are grown in the Great Plains. Before their general conversion to farmland, the Great Plains were noted for their extensive grasslands, from tallgrass prairie in the eastern plains to shortgrass steppe in the western High Plains. Elevation rises gradually from less than a few hundred feet near the Mississippi River to more than a mile high in the High Plains. The generally low relief of the plains is broken in several places, most notably in the Ozark and Ouachita Mountains, which form the U.S. Interior Highlands, the only major mountainous region between the Rocky Mountains and the Appalachian Mountains.
Is there an answer to this question: Before being converted to grassland the Great Plains were known for what?

Answer: unanswerable

Question: By 1860, Houston had emerged as a commercial and railroad hub for the export of cotton. Railroad spurs from the Texas inland converged in Houston, where they met rail lines to the ports of Galveston and Beaumont. During the American Civil War, Houston served as a headquarters for General John Bankhead Magruder, who used the city as an organization point for the Battle of Galveston. After the Civil War, Houston businessmen initiated efforts to widen the city's extensive system of bayous so the city could accept more commerce between downtown and the nearby port of Galveston. By 1890, Houston was the railroad center of Texas.
Is there an answer to this question: What type of roads didn't converge in Houston?

Answer: unanswerable

Question: On the northern outskirts of the city, Crownhill Fort is a well restored example of a "Palmerston's Folly". It is owned by the Landmark Trust and is open to the public.
Is there an answer to this question: What structure was referred to as a "Palmerston's Folly"?

Answer: Crownhill Fort

Question: Hunting and gathering was presumably the subsistence strategy employed by human societies beginning some 1.8 million years ago, by Homo erectus, and from its appearance some 0.2 million years ago by Homo sapiens. It remained the only mode of subsistence until the end of the Mesolithic period some 10,000 years ago, and after this was replaced only gradually with the spread of the Neolithic Revolution.
Is there an answer to this question: What began replacing hunting-gathering at the end of the Mesolithic period?

Answer:
Neolithic Revolution