The correct option is B
Consider the following histogram of the number of flights arrival per minute at different hours of the day in an airport:
When the center of top edges of each bar of a histogram is connected, a line graph is obtained as follows:
Here, the black line connected by orange dots is the line graph.
Histogram is generated form a grouped frequency table, which is continous.
Arrivals per minute
Hence, the obtained line graph is continuous.
But, in a bar graph, data points are at discrete data points.
Connecting the top edges of bars of a bar graph will not result in a proper line graph.
However, we can generate a histogram from a bar graph and finally plot a line graph.