The problem: Answer a question about this article:
Meanwhile, Elisha Gray was also experimenting with acoustic telegraphy and thought of a way to transmit speech using a water transmitter. On February 14, 1876, Gray filed a caveat with the U.S. Patent Office for a telephone design that used a water transmitter. That same morning, Bell's lawyer filed Bell's application with the patent office. There is considerable debate about who arrived first and Gray later challenged the primacy of Bell's patent. Bell was in Boston on February 14 and did not arrive in Washington until February 26.
What material did Elisha Gray use to convey sound?
****
The answer: water

The problem: Answer a question about this article:
The end of the Porfiriato came in 1910 with the beginning of the Mexican Revolution. Diaz had stated that Mexico was ready for democracy and he would step down to allow other candidates to compete for the presidency, but Diaz decided to run again in 1910 for the last time against Francisco I. Madero. During the campaign Diaz incarcerated Madero on election day in 1910. Diaz was announced the winner of the election by a landslide, triggering the revolution. Madero supporter Toribio Ortega took up arms with a group of followers at Cuchillo Parado, Chihuahua on November 10, 1910.
Who was incarcerated while running against Diaz?
****
The answer: Madero

The problem: Answer a question about this article:
Later, von Neumann suggested a new method of linear programming, using the homogeneous linear system of Gordan (1873), which was later popularized by Karmarkar's algorithm. Von Neumann's method used a pivoting algorithm between simplices, with the pivoting decision determined by a nonnegative least squares subproblem with a convexity constraint (projecting the zero-vector onto the convex hull of the active simplex). Von Neumann's algorithm was the first interior point method of linear programming.
What was von Neumann's method known to be the first of?
****
The answer: algorithm was the first interior point method of linear programming.

The problem: Answer a question about this article:
Underpinning Houston's land surface are unconsolidated clays, clay shales, and poorly cemented sands up to several miles deep. The region's geology developed from river deposits formed from the erosion of the Rocky Mountains. These sediments consist of a series of sands and clays deposited on decaying organic marine matter, that over time, transformed into oil and natural gas. Beneath the layers of sediment is a water-deposited layer of halite, a rock salt. The porous layers were compressed over time and forced upward. As it pushed upward, the salt dragged surrounding sediments into salt dome formations, often trapping oil and gas that seeped from the surrounding porous sands. The thick, rich, sometimes black, surface soil is suitable for rice farming in suburban outskirts where the city continues to grow.
The sand and clay deposited onto decaying marine matter transformed into what?
****
The answer:
oil and natural gas