add a variety of vitamins to the supplement test the supplement on mice in the laboratory develop packaging that is attractive to women test the supplement on a larger sample of women
I gave my students this multiple choice question: A dietary supplement manufacturer developed a new calcium supplement that appears to increase the bone density in middle-aged women. When tested in a small clinical trial, the supplement was shown to cause a 15% increase in bone density in 8 out of 10 women. Before the supplement is offered to the general public, which step should the manufacturer take next?

Only one answer is correct among these 4 choices:
- add a variety of vitamins to the supplement
- test the supplement on mice in the laboratory
- develop packaging that is attractive to women
- test the supplement on a larger sample of women

Could you tell me which one is correct?

test the supplement on a larger sample of women