Labeling it as "Evil" and "Un-evil" then asking us "which is more evil?" is something of a leading question. Really you should present it as two options and not already pre-suppose the morality of the people who take either course of action. Watch/read ZP's views on labeling moral choices; putting "Evil" and "Good" is stupid.
OT
If we KNOW the consequences of the course's of action then the clear, obvious winner is Option B; Less people die. Hell to call "Saving 150,000 people's lives" the "Evil" option is almost ridiculous.
If we don't know any of the consequences (Ie how many people will die in each scenario before a cure is found) then "Both" is my option. Volounteers can come forward for experimentation, but nobody should be forced.
I imagine we'll even out at 150,000 deaths in that scenario and everything turned out better than expected.