Correct Answer : Option (D) - Beryllium-7
Note : Lucrezia Terzi, a researcher at the Belgian Nuclear Research Centre (SCKCEN), has come up with a new way of predicting the monsoon at a science and technology conference organised in Vienna by the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO). The new method measures how much Beryllium-7 (an isotope of the element Beryllium) is present in the air. The Be-7 is chosen because it is created only in the stratosphere, when cosmic rays hit and break the nuclei of nitrogen and oxygen. Due to the sun warming the oceans differently at different latitudes, and the spin of the earth, water-bearing air moves up and down in circular fashions, which is the basic cause of the monsoons. When air flows down from the stratosphere (upwards of 33,000 feet from the earth's surface), it brings with it some Be-7. That makes the strong connection between the amount of Be-7 and the timing of monsoons.