A student measured the length of a rod and wrote it as $3.50\; cm$.What instrument did he use to measure it?

Question

$\begin{array}{1 1}(A)\;\text{A screw gauge having 100 divisions in the circular scale and pitch as 1 mm} \\ (B)\;\text{A screw gauge having 50 divisions in the circular scale and pitch as 1 mm} \\(C)\;\text{A meter scale} \\(D)\; \text{A vernier calliper where the 10 divisions in vernier scale matches with 9 divisions in main scale and mainscale has 10 divisions in 1 cm.} \end{array}$