Suppose Thailand produces only bikes and air fryers. The resources that are used in the production of these two goods are specializedthat is, some resources are better suited for producing bikes than air fryers, whereas others are better suited for producing air fryers than bikes. The shape of Thailand's production possibilities frontier (PPF) should reflect the fact that as Thailand produces more air fryers and fewer bikes, the opportunity cost of producing each additional air fryer is decreases or increase or remains constant