निम्नलिखित में से कौन सी शिक्षण पद्धति शिक्षक-केंद्रित पद्धति (teacher-centered method) के रूप में वर्गीकृत है?

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: