Answer:
A
Explanation:
Marginal utility is the satisfaction gotten from the consumption of one more additional product or service.
It indicates that the satisfaction gotten from an extra product consumed must be less than that derived from the previous product consumed.
from the question, 5 units of utility was derived from the consumption of a slice of pizza, and for two slices consumed, the utility dropped to 4units, which means consuming the third slice the satisfaction derived must be less than 4. if we add these values, 9+4+4 =13. This indicates that the total utility after the third slice must be less than 13.