Questions

In music, a fugue is a contrapuntal compositional technique in two or more voices, built on a subject that is introduced at the beginning in imitation and which recurs frequently in the course of the composition. 

Hence, the main theme of a fugue is called the subject.

Diego Garcia is a chain of Islands in the Indian ocean with large military base under British Indian Ocean Territory.

The U.S. military facility on the island of Diego Garcia in the Indian Ocean represents a horrific example of the human costs of war and imperialism.

Indian Navy’s survey vessel INS Sarvekshak has become the India’s first warship to install solar power system on board. The solar power system works on sunlight and hence is 100% per cent reliable for power source that can be used for communication equipment, battery charging and general lightings onboard round the clock with battery outputs during night. The system is maintenance free.

Hindol Sengupta

Settled agriculture was first seen in China around 6000 BC. The crops grown at this time were rice and millet.

Beginning in about 618 BC with classical millet agriculture, China's development of farming over the course of its history has played a key role in supporting the growth of what is now the largest population in the world.

The sentence that states the main idea of the paragraph is called as Thesis or the topic sentence.