Solution:
Given
Width of the continuous classes is 5
Frequency table is starting from 10
Total interval in a frequency distribution table is 5
Lower class-limit of the highest class?
Frequency distribution
10-15
15-20
20-25
25-30
30-35
According to above data
Highest class is 30-35 and lower class-limit of the highest class is 30, so b is correct.