On some days, Gustav makes his own salad for lunch, preferring to use either iceberg or romaine lettuce, topped off with lots of fresh tomatoes. For Gustav, the cross-price elasticity of demand for iceberg lettuce with respect to romaine lettuce is _____, and the cross-price elasticity of demand for iceberg lettuce with respect to tomatoes is _____. Question 9 Answer a. zero; positive b. positive; negative c. negative; positive d. negative; zero