The following is R code that would generate the plot in figure 2:

plot(1:3,1:3, col='blue', xlab='', ylab='')
points(1:2, 2:3, col='red')
polygon(x=c(2,2.5,3,2.5), y=c(1,2.5,1,1.5))
title(main='B', cex=3)