5. Don consumes bagels and cream cheese. He likes to place 2 ounces of cream cheese on each bagel, no more, no less. In this case, Don's indifference curves for bagels and cream cheese will be:

A) straight lines with slopes equal to -2

B) L-shaped, or right angles

C) upward-sloping

D) horizontal lines

E) vertical lines

*(Please explain why)*