Which of these options would increase the data$-$ink ratio of this chart?

This bar chart shows Satisfaction Score by Group. The groups are numbered $1$ through $7$ at the x axis, with numbers on the y axis ranging from $0$ to $90.$ The bars are in a light blue and the background is white with a pale grid. The top of each group bar displays the final value as a number.

a$.$ Removing the gridlines

b$.$ Including a subheading below the chart

c$.$ Changing the hue of the line