The law of diminishing marginal utility allow us to conclude that a) supply curves always slop upward b) total utility will always increase by an...

The law of diminishing marginal utility allow us to conclude that   a) supply curves always slop upward  b) total utility will always increase by an increasing amount as consumption increase.  c) a consumer will always buy positive amounts of all goods.    d) demand curves always slope downward and to the right