वह अवांछित चर जो किसी प्रयोग में परिणाम को प्रभावित करता है लेकिन सीधे प्रत्यक्ष रूप से नियंत्रित या प्रेक्षित नहीं होता है, क्या कहलाता है?

Match the types of variables in List-I with their description in List-II: List-I (Types of Variables) A. Independent variable in true experimental design B. Dependent variable C. Intervening variable D. Confounding variable List-II (Description) I. Outcome variable II. Control/Manipulated variable III. Spurious variable IV. Stands between independent variable and dependent variable

Many studies have shown that students score higher in mathematics tests when there is classical music playing in the background. Identify the independent variable in this context: