According to the passage, how are ants guided by trail pheromones?

After two decades of growing student enrollments and economic prosperity, business schools in the United States have started to face harder times. Only Harvard's MBA School has shown a substantial increase in enrollment in recent years. Both Princeton and Stanford have seen decreases in their enrollments. Since 1990, the number of people receiving Masters in Business Administration (MBA) degrees, has dropped about 3 percent to 75,000, and the trend of lower enrollment rates is expected to continue. There are two factors causing this decrease in students seeking an MBA degree. The first one is that many graduates of four-year colleges are finding that an MBA degree does not guarantee a plush job on Wall Street, or in other financial districts of major American cities. Many of the entry-level management jobs are going to students graduating with Master of Arts degrees in English and the humanities as well as those holding MBA degrees. Students have asked the question, "Is an MBA degree really what I need to be best prepared for getting a good job?" The second major factor has been the cutting of American payrolls and the lower number of entry-level jobs being offered. Business needs are changing, and MBA schools are struggling to meet the new demands. 

What is the main focus of this passage?

Which title best summarizes the main idea of the passage?

There are a number of natural disasters that can strike across the globe. Two that are frequently linked to one another are earthquakes and tsunamis. Both of them can cause a great amount of devastation when they hit. However, tsunamis are the direct result of earthquakes and cannot happen without them. The Earth has three main parts. They are the crust, the mantle, and the core. The crust is the outer layer of the Earth. It is not a single piece of land. Instead, it is comprised of a number of plates. There are a few enormous plates and many smaller ones. These plates essentially rest upon the mantle, which is fluid. As a result, the plates are in constant - yet slow - motion. The plates may move away from or towards other plates. In some cases, they collide violently with the plates adjoining them. The movement of the plates causes tension in the rock. Over a long time, this tension may build up. When it is released, an earthquake happens. Tens of thousands of earthquakes happen every year. The vast majority are so small that only scientific instruments can perceive them. Others are powerful enough that people can feel them, yet they cause little harm or damage. More powerful earthquakes, however, can cause buildings, bridges, and other structures to collapse. They may additionally injure and skill thousands of people and might even cause the land to change it appearance. Since most of the Earth's surface is water, numerous earthquakes happen beneath the planet's oceans. Underwater earthquakes cause the seafloor to move. This results in the displacement of water in the ocean. When this occurs, a tsunami may form. This is a wave that forms on the surface and moves in all directions from the place where the earthquake happened. A tsunami moves extremely quickly and can travel thousands of kilometres. As it approaches land, the water near the coast gets sucked out to sea. This causes the tsunamis to increase in height. Minutes later, the tsunami arrives. A large tsunami - one more than ten meters in height - can travel far inland. As it does that, it can flood the land, destroy human settlements, and kill large numbers of people.

Which of the following is NOT mentioned in paragraph 3 about earthquakes?

The tone of the passage is that of ................. 

The first songs of the Beatles were ................ 

The four boys of the Beatles ............... 

According to the author, M.L. ...............