Questions

Our Ex. Prime Minister Rajiv Gandhi was Pilot by profession before he entered politics.

The given sentence is in simple present tense and states a general fact, hence the latter half of the sentence with the blank will also be in the simple present tense. Since the subject in the latter part of the sentence is singular .i.e. 'the number', the verb will be followed accordingly. Hence, option 4 is the correct answer.

Transcription is a process of production of mRNA which occurs in the nucleus of the cell. After transcription, translation which occurs in the cytoplasm.

The United States subprime mortgage crisis was a nationwide financial crisis, occurring between 2007 and 2010, that contributed to the U.S. recession of December 2007 –June 2009.It was triggered by a large decline in home prices after the collapse of a housing bubble, leading to mortgage delinquencies and foreclosures and the devaluation of housing-related securities.