Which of the following s correct definition for Gauge factor?

• A. (incremental change in resistance due to strain/resistance of an unstretched wire)*(unstretched length of wire/incremental change in length)
• B. (resistance of an unstretched wire/incremental change in resistance due to stress)*(unstretched length of wire/incremental change in length)
• C. (incremental change in resistance due to stress/resistance of an unstretched wire)*(incremental change in length/unstretched length of wire)
• D. (incremental change in resistance due to stress/resistance of an unstretched wire)*(unstretched length of wire/incremental change in length)