Imagine We Took a Group of Smokers, Recorded How Many

Imagine we took a group of smokers, recorded how many cigarettes they smoked each day and then split them randomly into one of two 6-week interventions; 'hypnosis' or 'nicotine patch'. After the 6 weeks, we again recorded how many cigarettes they smoked each day and subtracted this number from the number of cigarettes they each smoked pre-intervention, to produce a intervention success score for each participant. Out of the following options, which would be the best method of displaying the results?

A) A simple bar chart with the variable 'intervention method' on the y-axis and 'intervention success' on the x-axis.
B) A simple boxplot with the variable 'intervention method' on the x-axis and 'intervention success' on the y-axis.
C) A clustered boxplot with 'intervention success' on the y-axis and 'intervention method' on the x-axis
D) A simple boxplot with the variable 'intervention method' on the y-axis and 'intervention success' on the x-axis.