Which of these is an example of periodic motion?

The picture shows the minute arm of a clock rotating.

Which type of motion does the rotation of the minute arm involve?

What type of motion does a spinning top show?

You are provided three scales $A$, $B$ and $C$ as shown in figure to measure a length of $10 \mathrm{cm}$.

For the correct measurement of the length, you will use the scale

The correct measurement of the length card in figure shown below is: