Cliffs can collapse because of the weather naturally eroding it. Also when water is constantly crashing against them, it can erode the layers of the cliff. It can also happen in a mud slide when the rain makes the soil extremely wet causing the rock to fall. Also in a rock slide when a piece of rock breaks off from the entire cliff.
The correct answer is - trade.
The Sumerians engaged in trade with their move of exchanging their surplus food for materials like the copper that they needed to develop their weapons and thus their army forces. This was a very smart move from their side because they managed to use the resource they had in abundance but was scarce in the other surrounding areas so that they take what they need to become stronger and pretty much defend more efficiently from the same people they were engaging in trade with.
King Henry VIII had Thomas More beheaded because Thomas More had refused to recognize the king as the head of the Church of England. Beheading was a common form of execution in those days. The correct answer is D.
