A student measured the length of a rod and wrote it as 3.50 cm. Which instrument did he use to measure it?
a. A meter scale.
b. A vernier calliper where the 10 divisions in vernier scale matches with 9 division in main scale and main scale has 10 divisions in 1 cm.
c. A screw gauge having 100 divisions in the circular scale and pitch as 1 mm.
d. A screw gauge having 50 divisions in the circular scale and pitch as 1 mm.