The Marginal Utility Curve for Units 6 Through 8 of Good

Multiple Choice

The marginal utility curve for units 6 through 8 of good Z lies below the horizontal axis. What does this imply must be true about the total utility curve for units 6 through 8 of good Z?

A) That portion of good Z's total utility curve must be upward sloping.
B) That portion of good Z's total utility curve must be downward sloping.
C) That portion of good Z's total utility curve must be horizontal.
D) That portion of good Z's total utility curve must also lie below the horizontal axis.