Rank each drug according to its ability to increase myocardial O2 demand: (potent -> least potent)

Scopolamine
Robinul
Atropine

a) Atropine > Robinul > Scopolamine
b) Scopolamine > Robinul > Atropine
c) Atropine > Scopolamine > Robinul
d) Robinul > Atropine > Scopolamine