The right option is; C. Bioelectrical impedance analysis
Bioelectrical impedance analysis is the least effective method for measuring body fat.
Bioelectrical impedance analysis is a method that is usually used for assessing body composition, specifically body fat. This method is commonly used because it is easy to use and its equipment is portable. Based on research, bioelectrical impedance analysis is considered as a method that is not effective and does not provide accurate measure of body composition because it is variable (its value changes). However, it is not a reference method.
