D and L configurations are relative configurations. Glucose and fructose both have −OH group on the bottom carbon to the right side. They have same D-configuration. Hence, they are called D-glucose and D-fructose. So, assertion (A) is true. Glucose rotates plane polarised light to the right side or clockwise direction. So, it is dextrorotatory. Whereas fructose rotates plane polarised light to left side or anti-clockwise. So, fructose is laevorotatory. So, given reason (R) is false.