Why I chose E.

Is my line of thinking okay here? If not, please let me know a better way to approach this. Thanks in advance. I chose E bc I thought it showed no cause, no effect. I figured that, to strengthen the cause and effect argument, if we remove the cause (the blanket) and show no effect (no reduced pain), that would strengthen that the blanket does in fact work. The placebo does not give the same effect as the blanket would in this case.