While eating at Alex's "Pizza by the Slice" restaurant, Kara experiences diminishing marginal utility. She gained 10 units of satisfaction from her first slice of pizza consumed, and would only receive 5 units of satisfaction from consuming a second slice. Based on this information we can conclude that:

A. Alex may have to lower the price to convince Kara to buy a second slice.
B. Kara will not eat a second slice, even if it is given to her at no charge.
C. Kara will definitely want to buy a second slice of pizza.
D. even if Kara buys a second slice, she will not buy a third slice

Since Kara (as everyone else) has diminishing marginal utility, she will only be willing to buy more pizza slices if their price lowers. This is always true because we assign value to goods and services depending on the satisfaction we get from them.

If she was really hungry, she was probably extremely satisfied by the first slice, but after that, the satisfaction only goes down. Some customers may need a few slices to start losing some satisfaction, but eventually everyone does.

That is the reason why many restaurants charge different prices depending on the size of the portion bought by the customer. This is exactly why many restaurants (specially fast food) have different promotions, e.g. the second milkshake or sandwich has a 30% discount.