18. Blood Pressure Meds A physician compared the effectiveness of two blood pressure drugs A and B using four pairs of identical twins—drug A was given to one twin; drug B to the other. If, in fact, there is no difference in the effects of the drugs, what is the probability that the drop in blood pressure for drug A is greater than the corresponding drop for drug B in all four pairs of twins? If you observed this result, would you think that drug A is more effective in lowering blood pressure than drug B?