The following table shows the class mark and frequency. Convert the table in the class interval
$\begin{array}{cc}\text{Class Mark}& \text{Frequency}\\ 55& 8\\ 65& 6\\ 75& 18\\ 85& 25\\ 95& 12\end{array}$

The correct option is B

$\begin{array}{cc}ClassInterval& Frequency\\ 50-60& 8\\ 60-70& 6\\ 70-80& 18\\ 80-90& 25\\ 90-100& 12\end{array}$

Since the difference between the two consecutive class mark is 10 , subtract $\frac{10}{2}$ = 5 from each class mark to get the lower limit and add 5 to each class mark to get the upper limit. Hence the table will be given as

$\begin{array}{cc}\text{Class Interval}& \text{Frequency}\\ 50-60& 8\\ 60-70& 6\\ 70-80& 18\\ 80-90& 25\\ 90-100& 12\end{array}$