A wooden box (open at the top) of thickness \[0.5\text{ }cm,\] length \[21\text{ }cm,\] width \[11\text{ }cm\] and height \[\text{6 }cm\] is painted on the inside. The expense for painting is \[Rs.\,70\]. What is the rate of painting per square centimetre?

• A.  \[Rs.\,0.7\]                                       
• B.  \[Rs.\,0.5\]       
• C.  \[Rs.\,0.1\]          
• D.         \[Rs.\,0.2\]