What would you say is the very best multivitamin for a young woman?

Many good choices: There is no one best multivitamin. For independent ratings of multivits see http://www.Multivitaminguide.Org/ any in the top 25 or so are good, but since 1/3 of people have difficulty converting Folic Acid to the active form l-5-mthf i advise one that has that such as ultranutrient by pure encapuslaions or ultrapreventive x by douglas. Most people need an extra 5000 iu of vit d in winter months.