The correct option is B 35 cm
7 meter = 700 centimeter
3 meters 85 centimeters = 385 centimeter
12 meters 95 centimeter = 1295 centimeter
Required length is the HCF of 700, 385 and 1295
HCF of 700, 385, 1295 is 35.
Therefore, required length is 35 cm.