To find the volume of a right rectangular prism (box), you use the formula:
\[ \text{Volume} = B \times h \times L \]
where:
- \( B \) is the breadth,
- \( h \) is the height,
- \( L \) is the length.
From the information given, you have:
- Breadth \( B = 21 \) cm
- Height \( h = 3 \) cm
However, the length \( L \) is not provided. Assuming it is missing, we cannot calculate the volume directly.
If you would like to provide the missing dimension or if any option is meant to imply the length, please clarify or provide that value. Otherwise, with just the breadth and height, the volume cannot be determined from the options given.