John will eat peanut butter and jelly sandwiches only when they are made with exactly two ounces of peanut butter and one ounce of jelly. If peanut butter is on the horizontal axis (P A. L-shaped, beginning at 2PB and 1J. B. a parallel straight line with a slope of –2. C. convex to the origin with a slope of –1/2. D. concave to the origin with a slope of –2.

Indifference Curve is the graph representing product combinations, which give consumers the same level of satisfaction. Its slope is Marginal Rate of substitution (MRS), which implies sacrifise of a good to gain other good, satisfaction level remaining same.

Perfect Complements are the goods, used jointly to satisfy a particular consumer want, in a particular ratio.

John eats peanut butter & jelly in a particular proportion of (2:1) ; this implies that these are perfectly complementary goods for John.

Perfect Complements have right angled or L shape indifference curve. Their slope i.e MRS = 0. Such, as the goods have zero substitutability, no amount of good one will be sacrifised to gain any amount of good two. They would only be used in a particular ratio, represented by a ray from origin, L mid point.

And the 'L curve' coordinates depend on the fixed ratio of their complementary use. So, it would be (PB,J) = (2,1)