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If "New Hair" work better than "Rogaine", more men in Group C would grow hair over their head than the amount of men in Group B would.

Explanation:

Since Dr. Rodriguez thinks her drug, the "New Hair" would work better than "rogaine", the result of the experiment should be "more men in Group C would grow hair over their head than the amount of men in Group B would". Therefor the whole hypothesis would be: If "New Hair" work better than "Rogaine", more men in Group C would grow hair over their head than the amount of men in Group B would.

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i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.

the real answer is b. scintillation counter