If there are only two goods, if more of good 1 is always preferred to less, and if less of good 2 is always preferred to more, then:
(a) indi erence curves slope downwards.
(b) indi erence curves slope upwards.
(c) indi erence curves may cross.
(d) indi erence curves could take the form of ellipses.
(e) None of the above.