Which of the following statements are true about the 'SWAYAM' platform? A. SWAYAM is designed to achieve three cardinal principles of education policy. B. SWAYAM hosts courses taught in classrooms from Class IX till Post-graduation. C. SWAYAM directly assesses students continuously and grants standard university degrees on its own. D. It can be accessed by anyone, anytime, at any place. Choose the most appropriate answer from the options given below:

The approach of combining multiple methods, data sources, or investigators in the study of the same sociological or scientific research phenomenon is known as:

Given below are two statements: Statement (I): The near-complete absence of fluoride in drinking water causes tooth decay. Statement (II): Excessive concentrations of fluoride in drinking water cause mottling of teeth, also known as dental fluorosis. In the light of the above statements, choose the most appropriate answer from the options given below: