_________ says that the marginal product of a factor input initially rises with its employment level. But after reaching a certain level of employment, it starts falling.
In the following question, four number pairs are given. The number on left side of (–) is related to the number on the right side of (–) with some Logic/Rule/Relation. Three are similar on basis of same Logic/Rule/Relation. Select the odd one out from the given options.