$3.$ A nonlinear cost related to order size is the cost of: a$.$ interest. b$.$ insurance. c$.$ taxes. d$.$ ordering. e$.$ space. $4.$ Linear programming to produce an aggregate plan: a$.$ will produce the best plan if accurate inputs are used. b$.$ is the most widely used technique. c$.$ is easy to implement. d$.$ will produce a plan that may not be the best plan. e$.$ requires an Excel spreadsheet.