What is recommerided amount of resistance and number of repetitions for improving muscular edurance A 80 - 100 percent B 40 - 60 percent C 40 - 60 percent D 70 -80 percent?

The recommended amount of resistance for improving muscular endurance is typically 40-60 percent of your one-repetition maximum (1RM). This resistance should be paired with higher repetitions, generally in the range of 12-20 or more. Therefore, the correct choice is B: 40 - 60 percent.